The rust-inhibiting properties of the all-stainless construction and the open frame build would lend well to a wet, sandy environment. However, with the use of the ATR, consider the following negative attributes of such a knife:
-For use in a maritime environment, the handles are not well-suited. This is because stainless steel handles are inherently slippery, whether they be slippery with lubricant, mechanical-related or sharpening oil, blood (from field dressing---I'm not trying to sound like a mall ninja

), or water. Are you sure stainless handles would have enough purchase and security when wet?
-When diving or kayaking, et cetera, do you wear gloves? And, if so, is the enlarged 14mm SpyderHole large enough to accomodate one-handed opening when panicked and cutting in an emergency? While I am a fan of the ATR and SALT (a Pacific is my current maritime EDC), you might consider a fixed blade knife for your life vest, buoyancy vest, or tank/rebreather harness. Having a fixed blade instead of a folding knife means you do NOT have to worry about cleaning inside the handles or maintaining/cleaning the locking mechanism. This also eliminates a great deal of time presenting the edge to the problem---that is, drawing a fixed blade is faster than drawing and opening a folder, and, as such, is less likely to drop in the water.
As an EDC, the ATR is an excellent knife with a strong lock, good VG10 steel, and a useful, utilitarian blade shape. Outfitted with a custom sheath where it is already in the open position with a Teklok and with a lanyard of parachute cord, it would be a formidable dive knife. But please consider the aforementioned points.
Enjoy your knife!
God bless you, America, and our men and women overseas.
KATN,
Wade
619G6