Marine

For use on a boat, select a model with low magnification for stability and the ability to work in low light, a 7x50 would be ideal. For a little more magnification consider a high quality 8.5x50 or 8x56

Select a waterproof model with a floatation strap, then, if the binocular goes overboard it will float until it is rescued!

A built in compass may also be useful.