These are the binoculars I use.
They are waterproof and fog proof and have a built-in illuminated compass. The rubber armored exterior makes them easy to hold in wet conditions. The compass appears at the bottom of the left eye piece and allows you to take bearings on aids to navigation. You may also use the bearing of another vessel to determine if there is a risk of collision.
The 50mm objective lens give you a bright image, especially useful in poor lighting conditions. For marine use, more that 7 power magnification becomes very difficult to hold steady.