Hollis DX 300X Drysuit with Neoprene Socks

Hollis DX-300X Dry Suit: Expedition-Grade Trilaminate Built for Technical Diving

The Hollis DX-300X is a trilaminate dry suit designed specifically for technical divers who spend serious time in demanding, cold, or contaminated water.

If you are pushing into overhead environments, doing deep decompression stops, or diving in conditions where a wetsuit simply stops being an option, this suit was built with you in mind.

It is not a recreational entry-level drysuit. The materials, construction choices, and feature set all reflect a suit designed to hold up over years of hard use, not occasional weekend dives.

The Three-Layer Shell

The DX-300X uses a trilaminate construction with a total material weight of 700 g/sq., which is on the heavier, more robust end of the trilaminate spectrum.

Each layer does a specific job:

• Outer layer: Heavy-duty Cordura Ripstop nylon. This is what takes the punishment. It resists punctures and abrasion, and the tear strength exceeds 300N (roughly 64.5 lbs.). For divers working around wreck structure, rock, or cave environments, that matters.
• Middle layer: 12-layer Butyl Mass. Butyl rubber is the waterproofing core of the suit. Twelve layers of it is a significant investment in long-term water integrity. Butyl also holds up well against chemical and ozone exposure, which is relevant if you dive in industrially affected or contaminated water.
• Inner liner: Silk-weave polyester. A smooth inner surface makes getting in and out of the suit easier, especially when you are suiting up solo or in a confined space.

Together, these layers make the DX-300X more durable than most trilaminates you will find at the recreational end of the market.

Freedom of Movement

Trilaminate suits have a reputation for feeling stiff and restrictive. Hollis addressed this directly in the DX-300X's design.

The suit panels are cut on the material bias, which means the fabric is oriented diagonally rather than straight. This gives the material more natural stretch. According to Hollis, the result is 25% more stretch than a traditionally cut trilaminate.

A telescopic torso adds to this. It allows the suit to extend and compress with your body as you move, while also letting it fit closer to your frame to reduce unwanted air migration inside the suit. Air migration, where your suit air shifts toward your feet or legs during certain positions, is something technical divers manage actively, and a closer fit helps.

The entry zipper runs diagonally across the front. A diagonal front zip is generally easier to self-don than a rear zip, and the low-profile YKK construction keeps the zipper flexible rather than rigid across your chest.

Seals

The DX-300X comes fitted with SiTech silicone neck and wrist seals. Silicone seals are softer and more comfortable against skin than latex for most divers, and they tend to last longer before cracking or degrading.

The neck uses SiTech's Neck Tite system, and the wrists use SiTech's Quick Cuff system. Both are designed for straightforward field replacement, which is useful when you are on a liveaboard or remote expedition and cannot easily get to a suit repair shop.

Inflation and Exhaust

The suit inflates via a chest-mounted valve and exhausts through a left shoulder-mounted dump valve. Chest inflation gives you a consistent, easy-to-reach connection point regardless of your configuration. Shoulder exhaust is a standard placement that works well in head-up and horizontal trim.

The included LP hose uses a 3/8-inch threaded quick-disconnect fitting, which connects to a standard low-pressure port on your first stage.

Pockets, Hardware, and Extras

The suit comes with two large bellow thigh pockets, each secured with hook-and-loop closures and fitted with internal D-rings. Bellow pockets expand to hold real gear, not just a slate. The D-rings give you a place to clip off small items inside the pocket.

Other details worth noting:

• Double-thickness 5mm neoprene kneepads protect the areas that take the most wear when you are kneeling on a boat deck or brushing against a surface underwater.
• Attached 5mm neoprene socks are integrated into the suit. You will still need to choose your dry suit boots or rock boots to go over them.
• 3M reflective safety strips improve your visibility to surface support and other divers in low-light or poor-visibility conditions.
• Internal adjustable suspenders help keep the suit positioned correctly on your body and reduce the suit from bunching or shifting during a dive.
• Wide flat-seam construction at the seams reduces the chance of leaks developing in the areas most prone to water ingress over time.

Fit and Sizing

The DX-300X is a unisex suit available in multiple sizes. Because trilaminate suits do not compress like neoprene, fit is more critical than with a wetsuit. A suit that is too large will trap excess air and make buoyancy control harder. One that is too small will restrict movement and fatigue you.

If you are between sizes or have an unusual body proportion, it is worth contacting Hollis or a dealer about custom sizing options before ordering.

Who This Suit Is Not For

If you are a recreational diver doing occasional cold-water dives, the DX-300X is more suit than you need. Its weight, durability, and price point reflect an expedition-grade build that makes most sense when you are putting a suit through sustained, demanding use.

Divers looking for a lighter trilaminate for warm-to-cool recreational diving will find other options that are easier to travel with and simpler to manage. The DX-300X earns its place in a kit when the conditions are genuinely harsh and the diving is genuinely technical.