Lock's that work underwater?

[Akimbo]

I don't know of any lock that will survive long in Salt water even a stainless steel one. There are a few metals made to truly withstand salt. I'm pretty sure they don't make locks from them.

Agreed, for tumbler lock designs anyway. Springs and cylinders would be very vulnerable. Another factor that I didn't see mentioned is marine growth, which would jam most any small mechanism and fill the keyhole in a matter of weeks.

You might be able to come up with a 3D printed mechanism that used a magnet to disengage a simple latch or dog. The inside of the box/housing could be filled with distilled water or fish oil to protect the works from corrosion, growth, and particulate contamination.

 

[JXT71]

When we had to use locks for diving at work, the only true lock with key we used were for lockout/tagout areas. The keys stayed with the diver. The locks never entered the pool, but did get wet with salt water and had to get sprayed with WD40 now and again. For the stuff underwater we used threaded hardware; stainless quick links or nuts and bolts. Maybe less secure, but who's going out of their way to bring a crescent wrench or two on a dive?

 

[chillyinCanada]

When we had to use locks for diving at work, the only true lock with key we used were for lockout/tagout areas. The keys stayed with the diver. The locks never entered the pool, but did get wet with salt water and had to get sprayed with WD40 now and again. For the stuff underwater we used threaded hardware; stainless quick links or nuts and bolts. Maybe less secure, but who's going out of their way to bring a crescent wrench or two on a dive?

The folks on their second dive having seen the bootie on their first dive.

 

[AfterDark]

When we had to use locks for diving at work, the only true lock with key we used were for lockout/tagout areas. The keys stayed with the diver. The locks never entered the pool, but did get wet with salt water and had to get sprayed with WD40 now and again. For the stuff underwater we used threaded hardware; stainless quick links or nuts and bolts. Maybe less secure, but who's going out of their way to bring a crescent wrench or two on a dive?

The OP wasn't concerned with someone taking it he wanted to secure it to keep it one place from water action but that in 2006.

 

[Jcp2]

The folks on their second dive having seen the bootie on their first dive.

Torx heads. Then they’ll have to come back another trip.