Mares Maximus Scuba Diving Knife

The Mares Maximus is a double-edged dive knife with a 440 stainless steel blade, a PVD coating over it and a Cordura sheath that straps to your arm or your ankle. Mares lists its use case as a multifunctional underwater tool rather than a pure cutting blade, and the extras back that up: the tip is ground to work as a screwdriver, and there is a bottle opener on the body. It is a knife for recreational divers who want one tool that deals with a snagged line and with the small jobs afterwards.

Who this suits

If you dive salt water often and want a cutting tool you can reach without unclipping anything, this covers it. The sheath runs on belt loops and mounts on the arm or the ankle, so you can put the knife where your rig has room rather than where the knife insists.

It also suits divers who like one item doing several jobs. The screwdriver tip and the bottle opener are not why you buy a dive knife, but they are why this one stays in the boat bag between trips.

Skip it if you run a stripped-down rig and count every gram, or if you want titanium rather than coated stainless. Skip it too if you need the dimensions before you commit. Mares' spec rows for the Maximus cover the materials, the edges and the mounting, and give no blade length, thickness or weight at all.

Two edges, two jobs

The blade is double-edged, one serrated side and one straight side, and Mares gives each side a job: the serrated edge for tough cutting tasks, the straight edge for precise cuts.

In the water that means you are not choosing your cutting style before you get wet. Braided line, netting and old rope come apart under a saw stroke on the serrated side. A strap, a zip tie or a length of monofilament cuts cleaner under one pull on the straight side. Both live on the same blade, so the choice happens when you need it, one-handed, with nothing to swap.

440 stainless, and what the coating adds

The blade is 440 stainless steel, the workhorse grade for dive knives, chosen because it takes a usable edge and holds off rust. The grade is not a promise though. Stainless resists corrosion, it does not ignore it.

That is what the coating is for. PVD, physical vapour deposition, bonds a thin hard layer onto the metal, and Mares rates the corrosion resistance of the finished blade as high on the strength of it. On a knife that lives in a wet sheath on a salt-water boat, that layer is the difference between a blade that still looks like a blade after a season and one that starts freckling early. Rinse it in fresh water anyway.

The sheath and where it rides

The sheath is Cordura with belt loops, and Mares lists arm or ankle as the mounting options.

Cordura is a woven nylon that takes abrasion and salt without going brittle, which counts for more on a sheath than on most soft kit, because the sheath is the part that gets dragged across a boat deck. Belt loops keep the mounting simple and repairable: webbing through a loop, no proprietary clip to lose in the surf.

Arm mounting puts the handle where either hand can find it without you folding up to reach. Ankle mounting keeps it clear of your chest and out of the way on entries, at the cost of a longer reach when it matters. Which one you pick usually comes down to what is already strapped to your legs.

The bottom line

The Maximus is a sensible one-knife answer for recreational salt-water diving: two edges that cover most cutting, a coated stainless blade built for the environment, and a sheath you can mount where your kit has space. The screwdriver tip and the bottle opener are real conveniences rather than reasons to buy. What it is not is a fully specified blade, because Mares publishes no length, thickness or weight for this model, so if those figures decide your purchase you will need them from the retailer. It is also not titanium, and coated stainless still wants a rinse after every dive.

Specifications