You cannot use just any other type of binoculars in wet conditions. When you’re boating or fishing, for instance, waterproof binoculars are best for you; they are also useful for hiking, hunting, and other activities in which you and your equipment are exposed to moisture or rain. Every good pair of waterproof binoculars has the following features, which make them efficient in wet environments:
Nitrogen Filling: The gaps inside waterproof binoculars are often charged with nitrogen, since the gas is resistant to condensation. Make sure that your binoculars have sealed nitrogen to prevent moisture build-up, which will subsequently leave streaks on your lenses and damage your binoculars.
Multi-layer coating: The coating outside the lenses of your waterproof binoculars has two functions. First it improves the amount of light passing through the lenses and the brightness of the view. It also makes the lenses more resistant to forming water droplets on their outer side.
Goggle design: It is also better for the eyepiece of waterproof binoculars to have a goggle designs. This eliminates the gap between your eyes and the eyepiece, as seen in other models. Non-goggle designs are always prone to having water or fog on the eyepiece, which can lead to unclear vision.
Rugged casing: The material of the case should primarily be water resistant, and its seams should also be sealed to prevent penetration of water and the leak of the nitrogen content. Rugged casing makes binoculars less prone to damage such as scratches and drops.
Porro prisms: Waterproof binoculars usually employ this kind of prism lens, which are mostly heavier and bigger than roof prisms. The extra effort of carrying these binoculars allows you to have a bright view despite poor weather conditions since porro prisms allow more light to pass through the lenses.
The real measure of a good pair of waterproof binoculars is not only their capacity to block water from entering their body; you also need to look at their efficiency in preventing moisture in and out of the lenses, and their capability to deliver a bright view despite low lighting conditions.