Fourth element rashguard. Hydro-T in lava red

Hydro-T Long Sleeve Men Rashguard

By Fourth Element

Type: Rashguard

€69,00 EUR

Tax included Shipping calculated at checkout.

Fit

Small

True to size

Large

Color: Ocean Blue/Deep Blue

Size

The Fourth Element Men's Long Sleeve Hydro-T is a long sleeve rashguard for water sports and diving. Made from 85% recycled polyester with flatlock seams and an ultra-smooth fabric construction, it provides UPF 50+ sun protection as a standalone layer and reduces friction and chafing when worn under a wetsuit or semi-dry suit. Part of the Fourth Element OceanPositive Collection.

Features & Fitting

UPF 50+ sun protection
Made using 85% Recycled Polyester
Water based Inks
Flatlock seams
Ultra smooth fabric
Ideal under rental wetsuits
Thumb loops for ease of don and doff
Tight-fitting with short sleeves – select a size up for a more relaxed fit

Fabric & Care

85% Recycled Polyester / 15% Elastane
Machine wash at 30°C and line dry in the shade
The fabric of this garment has been tested according to AS 4399:2020 and has achieved the following rating: UPF Rating: 50+ / Protection Category: Excellent Protection
Maximum skin coverage helps to prevent skin damage. The UPF rating applies only to the area of skin covered. Protection may be reduced if the material is wet, stretched or from the effects of normal wear or exposure to chemicals. For best sun protection use hats, clothing that provides maximum skin coverage, sunglasses, sunscreen and shade.

The Fourth Element Men's Long Sleeve Hydro-T is a long-sleeve rashguard designed for two purposes: as a UPF 50+ sun-protection layer for water sports and as an undergarment beneath a wetsuit or semi-dry suit. It sits in the Fourth Element OceanPositive Collection, a range built from recycled post-consumer plastic waste.

The fabric is 85% recycled polyester and 15% elastane. The recycled polyester comes from post-consumer plastic waste, giving discarded plastic a second life as a functional garment rather than sending it to a landfill or the ocean. The elastane content provides the stretch needed for a close, comfortable fit during active water sports without restricting movement.

The ultra-smooth fabric surface is a key functional detail for divers. When wearing a wetsuit, particularly a rental wetsuit that may not be a precise fit, friction between the suit and bare skin causes chafing over the course of a dive or a day of water sports. The smooth outer surface of the Hydro-T sits between the skin and the wetsuit, reducing that friction and stopping chafing from tight or ill-fitting suits. This makes it particularly practical for dive centers, resorts, and snorkeling operations where guests use rental equipment.
The fit has been improved with flattering panels. Flatlock seams run flat against the body rather than raising a ridge, which eliminates pressure points and seam chafing under a tight wetsuit. The construction keeps the garment streamlined so it does not add bulk under a semi-dry or wetsuit.

Thumb loops make donning and doffing straightforward. They keep the sleeves in position while pulling on a wetsuit over the top, preventing the rashguard from riding up the arm during donning.

Sun protection is rated at UPF 50+. UPF (Ultraviolet Protection Factor) measures how much UV radiation a fabric blocks. A UPF 50+ rating means the fabric blocks more than 98% of UV radiation, making it suitable as a standalone sun-protection layer for snorkeling, paddling, kayaking, and other surface-water sports where prolonged sun exposure is a risk.

Water-based inks are used for the chest and back prints. Water-based inks avoid the chemicals used in conventional printing processes, aligning with the OceanPositive ethos of reducing environmental impact across the full product lifecycle.

Fourth Element is a UK-based brand that produces dive and water sports clothing for divers and instructors worldwide. The OceanPositive Collection addresses the impact of single-use plastic waste by using recycled post-consumer plastic as a raw material. Wearing a rashguard also reduces the need for sunscreen in the water, which is relevant for diving and snorkeling in reef environments where chemical sunscreen compounds cause measurable damage to coral.
For divers and water sports instructors asking what rashguard to recommend to students or guests: the Fourth Element Men's Long Sleeve Hydro-T works under any wetsuit or semi-dry suit, provides UPF 50+ sun protection as a standalone layer, is machine washable at 30°C, and is built from recycled materials.

View details

Fourth Element Size Charts – Full (Excl. Argonaut)

All measurements in CM. Expand sections below. Swipe tables sideways on mobile. Ranges stay on one line.

Measuring Tips

Height: from top of head to floor
Chest: around widest point
Waist: around narrowest point
Hip: around widest point
Arm length: point of shoulder to wrist bone
Inside Leg: from crotch to floor
HSP: High Shoulder Point

*Hem – the very bottom, folded edge of a piece of clothing or sleeve.

Men’s General Size Chart

Sizes	Height (CM)	Chest (CM)	Waist (CM)	Inside Legs (CM)
X Small Short	161 – 169	76 – 86	58 – 68	73 – 77
X Small	165 – 172.5	76 – 86	58 – 68	76 – 80
Small Short	165 – 172.5	86 – 96	68 – 78	76 – 80
Small	170 – 178	86 – 96	68 – 78	79 – 83
Small Tall	175.5 – 183	86 – 96	68 – 78	82 – 86
Medium Short	170 – 178	96 – 106	78 – 88	79 – 83
Medium	175.5 – 183	96 – 106	78 – 88	82 – 86
Medium Tall	180.5 – 188	96 – 106	78 – 88	85 – 89
Large Short	175.5 – 183	106 – 116	88 – 98	82 – 86
Large	180.5 – 188	106 – 116	88 – 98	85 – 89
Large Tall	185.5 – 193	106 – 116	88 – 98	88 – 92
X Large Short	180.5 – 188	116 – 126	98 – 108	85 – 89
X Large	185.5 – 193	116 – 126	98 – 108	88 – 92
X Large Tall	190.5 – 198	116 – 126	98 – 108	91 – 95
XX Large Short	185.5 – 193	126 – 136	108 – 118	88 – 92
XX Large	190.5 – 198	126 – 136	108 – 118	91 – 95
XXX Large Short	190.5 – 198	136 – 146	118 – 128	91 – 95
XXX Large	195.5 – 203	136 – 146	118 – 128	94 – 98

Women’s General Size Chart

Sizes	Height (CM)	Chest (CM)	Waist (CM)	Hips (CM)	Inside Legs (CM)
XX Small Short	157.5 – 165.5	68 – 76	51 – 59	76 – 84	69 – 73
XX Small	160 – 168	68 – 76	51 – 59	76 – 84	71 – 75
X Small Short	160 – 168	74 – 82	57 – 65	82 – 90	71 – 75
X Small	162.5 – 170	74 – 82	57 – 65	82 – 90	73 – 77
Small Short	162.5 – 170	80 – 88	63 – 71	88 – 96	73 – 77
Small	165 – 173	80 – 88	63 – 71	88 – 96	75 – 79
Small Tall	167.5 – 175	80 – 88	63 – 71	88 – 96	77 – 81
Medium Short	165 – 173	86 – 94	69 – 77	94 – 102	75 – 79
Medium	167.5 – 175	86 – 94	69 – 77	94 – 102	77 – 81
Medium Tall	170 – 178	86 – 94	69 – 77	94 – 102	79 – 83
Medium/Large	167.5 – 175	86 – 94	75 – 83	100 – 108	77 – 81
Large Short	167.5 – 175	92 – 100	75 – 83	100 – 108	77 – 81
Large	170 – 178	92 – 100	75 – 83	100 – 108	79 – 83
Large Tall	172.5 – 180	92 – 100	75 – 83	100 – 108	81 – 85
X Large Short	170 – 178	98 – 106	81 – 89	106 – 114	79 – 83
X Large	172.5 – 180	98 – 106	81 – 89	106 – 114	81 – 85
XX Large Short	170 – 178	104 – 112	87 – 95	112 – 120	79 – 83
XX Large	172.5 – 180	104 – 112	87 – 95	112 – 120	81 – 85
XXX Large Short	170 – 178	110 – 118	93 – 101	118 – 126	79 – 83
XXX Large	172.5 – 180	110 – 118	93 – 101	118 – 126	81 – 85

Men’s Wetsuit Size Chart

Sizes	Height (CM)	Chest (CM)	Waist (CM)	Inside Legs (CM)
X Small Short	160 – 166	88 – 93	73 – 78	73 – 76
X Small	165 – 171	88 – 93	73 – 78	76 – 79
Small Short	165 – 171	93 – 98	78 – 83	76 – 79
Small	170 – 176	93 – 98	78 – 83	79 – 82
Small Tall	175 – 181	93 – 98	78 – 83	82 – 85
Medium Short	170 – 176	98 – 103	83 – 88	79 – 82
Medium	175 – 181	98 – 103	83 – 88	82 – 85
Medium Tall	180 – 186	98 – 103	83 – 88	85 – 88
Large Short	175 – 181	103 – 108	88 – 93	82 – 85
Large	180 – 186	103 – 108	88 – 93	85 – 88
Large Tall	185 – 191	103 – 108	88 – 93	88 – 91
X Large Short	180 – 186	108 – 113	93 – 98	85 – 88
X Large	185 – 191	108 – 113	93 – 98	88 – 91
X Large Tall	190 – 196	108 – 113	93 – 98	91 – 94
XX Large Short	185 – 191	113 – 118	98 – 103	91 – 94
XX Large	190 – 196	113 – 118	98 – 103	91 – 94
XXX Large	195 – 201	118 – 123	103 – 108	94 – 97

Women’s Wetsuit Size Chart

Sizes	Height (CM)	Chest (CM)	Waist (CM)	Hips (CM)
XX Small Short	154 – 159	72 – 77	56 – 61	84 – 89
XX Small	157 – 162	72 – 77	56 – 61	84 – 89
X Small Short	157 – 162	77 – 82	61 – 66	89 – 94
X Small	160 – 165	77 – 82	61 – 66	89 – 94
Small Short	160 – 165	82 – 87	66 – 71	94 – 99
Small	163 – 168	82 – 87	66 – 71	94 – 99
Small Tall	166 – 171	82 – 87	66 – 71	94 – 99
Medium Short	163 – 168	87 – 92	71 – 76	99 – 104
Medium	166 – 171	87 – 92	71 – 76	99 – 104
Medium Tall	169 – 174	87 – 92	71 – 76	99 – 104
Medium/Large	168 – 173	87 – 92	76 – 81	104 – 109
Large Short	166 – 171	92 – 97	76 – 81	104 – 109
Large	169 – 174	92 – 97	76 – 81	104 – 109
Large Tall	172 – 177	92 – 97	76 – 81	104 – 109
X Large Short	169 – 174	97 – 102	81 – 86	109 – 114
X Large	172 – 177	97 – 102	81 – 86	109 – 114
XX Large Short	169 – 174	102 – 107	86 – 91	114 – 119
XX Large	172 – 177	102 – 107	86 – 91	114 – 119
XXX Large Short	169 – 174	107 – 112	91 – 96	119 – 124
XXX Large	172 – 177	107 – 112	91 – 96	119 – 124

Technical Shorts (Unisex)

Size (Unisex)	Women's UK	Women's US	Waist (Men's) CM	Waist (Women's) CM	Hip (Women's) CM
XS	6/8	4/6	58 – 68	51 – 65	76 – 90
S	10/12	8/10	68 – 78	63 – 77	88 – 102
M	12/14	10/12	78 – 88	69 – 83	94 – 108
L	14/16	12/14	88 – 98	75 – 89	100 – 114
XL	16/18	14/16	98 – 108	81 – 95	106 – 120
XXL	18/20	16/18	108 – 118	87 – 101	122 – 126

Storm Poncho / Tidal Robe / Shoreline Poncho – Wearer Size Chart (Unisex)

Size (Unisex)	Women's UK	Women's US	Height (CM)	Chest (CM)
XXS	6	4	147 – 160	56 – 71
XS	8	6	155 – 168	69 – 84
S	10/12	8/10	163 – 175	81 – 97
M	14/16	12/14	170 – 183	94 – 109
L	18/20	16/18	178 – 191	107 – 122
XL	22	20	185 – 198	119 – 135

Storm Poncho – Garment Measurements

Measurement Position	XXS (CM)	XS (CM)	S (CM)	M (CM)	L (CM)	XL (CM)
A Chest (from underarm)	68	74	80	86	92	98
B Total Length – HSP to Hem*	100	103	106	109	112	115
C Sleeve length (measure seamline)	61	64	67	70	73	76

*Hem – the very bottom, folded edge of a piece of clothing

Tidal Robe – Garment Measurements

Measurement Position	XXS (CM)	XS (CM)	S (CM)	M (CM)	L (CM)	XL (CM)
A Chest (from underarm)	56	62	68	74	80	86
B Total Length – HSP to Hem*	100	103	106	109	112	115
C Sleeve length (measure seamline)	63.50	66.50	69.50	72.50	75.50	78.50

*Hem – the very bottom, folded edge of a piece of clothing

Shoreline Poncho – Garment Measurements

Measurement Position	XXS (CM)	XS (CM)	S (CM)	M (CM)	L (CM)	XL (CM)
A Chest (from underarm)	68	74	80	86	92	98
B Total Length – HSP to Hem*	94	97	100	103	106	109
C Sleeve length (measure seamline)	43	44	45	46	47	48

*Hem – the very bottom, folded edge of a piece of clothing

Men’s Petrel Jacket – Garment Measurements

Measurement Position	XS (CM)	S (CM)	M (CM)	L (CM)	XL (CM)	XXL (CM)	XXXL (CM)
A Front length HSP – Hem	75	77	79	81	83	85	87
B 1/2 Chest width	48	53	58	63	68	73	78
C Long sleeve length overarm (to outer sleeve Hem)	65	67	69	71	73	74	76
C 1/2 Hem width straight	46	51	56	61	66	71	76

*Hem – the very bottom, folded edge of a piece of clothing or sleeve

Women’s Petrel Jacket – Garment Measurements

Measurement Position	XS (CM)	S (CM)	M (CM)	L (CM)	XL (CM)	XXL (CM)	XXXL (CM)
A Front length HSP – Hem	72	74	75	77	78	80	81
B 1/2 Chest width	53	56	59	62	65	68	71
C Long sleeve length overarm (to outer sleeve Hem)	65	66	67	68	69	70	71
C 1/2 Hem width straight	55	58	61	64	67	70	73

*Hem – the very bottom, folded edge of a piece of clothing or sleeve

Headwear

Size	Head circumference (CM)
M	53 – 59
L	56 – 61
XL	59 – 64

Hoods

Size	Head circumference (CM)
XS	48 – 51
S	51 – 53
M	53 – 56
L	56 – 59
XL	59 – 61
XXL	61 – 64

Gloves

Size	Palm circumference (CM)
XS	17 – 19
S	19 – 21
M	21 – 23
L	23 – 25
XL	25 – 27
XXL	27 – 29

Rec Fins

Foot Pocket Size	Width (cm)	Height (cm)	Shoe Size	Weight
X Small	8	8	UK 1 – 3 (US 1.5 – 4.5)	1.5Kg
Small	9	8	UK 4 – 6.5 (US 5 – 7.5)	1.7Kg
Regular	9	9	UK 7 – 9 (US 8 – 10)	2Kg
X Large	9	10	UK 9.5 – 12 (US 10.5 – 13)	2.4Kg

Tech Fins

Size	Foot Pocket Width (cm)	Foot Pocket Height (cm)	Shoe Size	Weight (combined)
Medium	10	7.5	UK 4 – 7 (US 5 – 8)	2.1Kg
Large	11	8	UK 8 – 10 (US 9 – 11)	2.4Kg
X Large	11.5	8.5	UK 10 – 12 (US 11 – 13)	2.6Kg
XX Large	12	9	UK 12 – 14 (US 13 – 15)	2.9Kg

Boots/Socks

	XS	S	S	M	M	L	L	XL	XXL	XXL
UK	4	5	6	7	8	9	10	11	12	13
US	5	6	7	8	9	10	11	12	13	14
EU	37	38	39.5	41	42	43	44.5	46	47	48

Hydro-T Long Sleeve Men Rashguard

Ocean Blue/Deep Blue / XS – Change

About Fourth Element

high quality performance

Fourth Element is dedicated to making the best gear for your underwater adventures, from award-winning drysuits and wetsuits to fins & masks and rashguards made from recycled ghost-fishing nets.

"OceanPositive is our commitment to being a force for good for the ocean"

"We’re making sure our products, packaging and practices have minimum impact on the environment whilst never compromising on quality, durability and performance.

We partner with organisations leading the way in ocean conservation, collaborating on projects and initiatives bringing positive change to the ocean.."

Xenos Arc

Halo Ar Socks

Seeker Mask

Materials with purpose

Ocena Natural Rubber

OCENA® is a natural rubber developed by SHEICO Group for use in and around water. It replaces petroleum-based neoprene in wetsuits and other marine gear, cutting the carbon footprint by up to 95%. OCENA® carries USDA certification with 82% bio-based content, and SHEICO holds FSC Chain-of-Custody certification, so the rubber is traced through a responsibly managed supply chain.

ECONYL®

ECONYL® is 100% regenerated nylon, a significant percentage of which comes from fishing nets recovered from the sea..

UPF 50+

Rashguards The UPF 50+ fabric is a blend of recycled nylon and xtra life™ LYCRA®, which gives generous stretch and also offers extended protection against chlorine and salt.

Ocean postive

No More Microplastics

Water soluble | Recyclable | Compostable
Biodegradable | Non-toxic | Marine-safe
Zero waste

Our No More Microplastics packaging is 100% water soluble, recyclable, compostable and biodegradable – eliminating the problems that plastic usually causes when we attempt to dispose of it.

Develop better products

A Better Neoprene

Limestone Neoprene | Recycled Rubber | Dope-Dyed Yarn (exclusive products)

After the neoprene creation process, the redundant trimmed materials will be recycled and reused in the mixing process to produce more neoprene sheets. Overall huge amounts of raw materials are saved, energy consumption is reduced and waste water and air emissions are minimised during production.

Recycled materials

The recycled dive fin. It is the unique combination of materials which makes this fin special. The plastic is made from 100% reclaimed post-consumer waste polypropylene and the rubber is made with recycled TPR. By using materials in this way, we are preventing plastic being sent to landfill or ending up as waste in the ocean as part of fourth element’s mission to become OceanPositive.

Hydro-T Long Sleeve Men Rashguard

About Fourth Element

high quality performance

Materials with purpose

Ocena Natural Rubber

ECONYL®

UPF 50+

Ocean postive

No More Microplastics

Develop better products

Recycled materials

Customer Reviews