I am not familiar with that particular Nikon but here is some information on the Pentax.
Pentax 7x50 PCF WP
Fully waterproof, nitrogen-filled body, outstanding optical performance with aspherical optical elements. In addition, they are fully encased in a protective rubber housing. Because of their rugged waterproof and fog-proof design, the PENTAX PCF WPs are ideal for use around and on the water, as well as for observations in harsh weather and extreme climates.
- The waterproof and fogproof body of these PCF WP models is rated JIS Class 6 (submersible down to 1 meter depth of water), allowing them to be washed clean when they get dirty or are accidentally soaked in salt water.
- They have fully multi-coated optics to eliminate harmful ultraviolet rays while improving light transmission for high contrast images with no glare or flare.
- High quality BaK-4 prisms transmit more light at the edges to enhance illumination for easier viewing in dim light.
- Aspherical optical elements to produce clear, bright images with minimal distortion.
- Long eye relief of 20mm or longer, making it easier for the user to see the image even when the eyes are moved away from the eyepieces. This feature is especially convenient for those who wear eyeglasses.
- A mechanical focus lock feature allows users to lock in at a specific distance for convenient focus-free viewing.
- Click-stop diopter adjustment locks in right eyepiece diopter setting.
- Ruggedly constructed with rubber covering to protect the optical and mechanical systems.
- The rubber slide-style eyecups are easily pulled out providing easier image viewing for eyeglass wearers. In addition, the eyepiece caps are designed to double-function as rain shields to make viewing easier in the rain or snow.
- Combine the built-in tripod socket with a tripod and the optional Tripod Adapter-N to stabilize the binoculars and prevent unwanted shake, making extended observations easy and comfortable.
- As with all Pentax binoculars, they are protected by a limited lifetime warranty.