Caiman 40 Large Waterproof Backpack

Expedition-grade waterproof protection. Built for hard use.

Fully welded waterproof main compartment
No stitching. No leaks. Keeps your kit dry in sustained heavy rain and rough conditions.
Built for heavy loads and long days
Padded shoulder straps, sternum strap, waist strap and airflow back panel for serious comfort on the move.
Fully customisable external carry
MOLLE/PALS webbing, daisy chains and elasticated front webbing for attaching wet, bulky or specialist kit.

£79.95 GBP

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Available now! Order yours today with free delivery.

Color: Jungle Green

"This is the second bag I've bought. Superb quality. Well worth the money."
Barrie Gunn, verified buyer

Built for the kind of days where your gear needs to work as hard as you do.
The Caiman 40 is a fully welded, expedition-grade waterproof backpack designed for demanding conditions, heavy loads and years of hard use. Its 40-litre main compartment keeps your kit dry in sustained heavy rain, rough terrain and extended time outdoors.

Adjustable roll-top closure.
The roll-top design allows flexible capacity and can be secured in multiple configurations: clipped above, to the side, or compressed using the over-the-top webbing straps. No zips. No weak points. Just a clean, reliable seal.

Built for exposed environments.
Suited to multi-day expeditions, hiking, fishing, paddling and backcountry travel, the Caiman 40 prioritises waterproofing, durability and external carry over internal organisation. This is a bag for serious use in serious conditions.

Supportive load-carry system.
For longer wear and heavier loads, the Caiman 40 includes padded shoulder straps with D-ring attachment points, a sternum strap, waist strap and airflow back panel — designed for comfort across long days and difficult terrain.

Fully customisable external carry.
MOLLE/PALS webbing, daisy chains and elasticated front webbing let you attach wet, bulky or specialist kit externally. Two large bottle pockets keep hydration accessible without compromising the waterproof main compartment.

Choosing between the Caiman 40 and Aonyx 25?
The Caiman 40 is built for demanding outdoor use — it prioritises waterproofing, durability and external carry over internal organisation. It does not include a padded laptop sleeve and is not designed for everyday commuting or office use.

If you regularly carry electronics or need daily organisational features, the Aonyx 25 may be more suitable.

For a detailed breakdown of capacity, structure and use case, read our Caiman 40 vs Aonyx 25 comparison guide.

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Order with confidence

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All payments processed securely through our website.
Fast UK delivery
Free UK shipping. Most orders arrive within 3 working days.
Field-tested. Built to last.
Used on real expeditions. Designed for years of hard use.

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Caiman 40 Large Waterproof Backpack

Product Information

Care Guide

Rinse any dirt or salt off with fresh water.
Dry thoroughly before storing.

Additional Information

Electrical items such as mobile phones should be placed inside a suitably IP rated container within the dry bag to avoid accidental water damage.

This rucksack is not rated for submersion.

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Testimonials

★★★★★
Amazon Expedition Proven

Just returned from an expedition into the Amazonian jungle in Guyana, fly fishing for Arapaima.
Bought the Aonyx 25 waterproof backpack to protect expensive gear from the elements ... item performed flawlessly.

JDA

Purchased the Aonyx 25
★★★★★
Reliable in Real Conditions

Fantastic product. Purchased this rucksack for Wildfowling trips as some of my friends have them.
Great product. Easy to wash down. Quick to dry. Keeps all the contents dry. Pockets for flask and water bottle are great.

Peter Catling

Purchased the Caiman 40
★★★★★
Monsoon Tested at Mont Blanc

Bought two 60L waterproof duffels for our trip through France and Italy. We drove down to Mont Blanc with
both bags strapped onto the luggage rack. Went through a monsoon on first day down to Mont Blanc and the bags were fantastic. Everything inside bone dry.

Nigel N

Purchased the Aonyx 60

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Caiman 40 Backpack

Product FAQs

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How long does delivery take?

We aim to dispatch orders on the same or next working day. Free delivery takes 2-4 working days. Express delivery takes 1-3 working days.

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How is this bag waterproof?

The main body of the backpack is made from a PVC tarpaulin material, which is completely waterproof. Rather than using traditional stitched seams the Caiman has welded joins which effectively make it seamless to the roll top.

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Is it submersible?

No we don't recommend full submersion of this backpack as it is a roll top and has no zip seal.

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IS the front zip waterproof?

No, it's only water resistant.

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