Nikon's family waterproof compact of 2013 — 10MP CCD, 29-87mm equiv zoom, 5m waterproof, 720p video
The Coolpix S31 was a family-oriented waterproof compact launched by Nikon in 2013. Rather than a hardcore adventure camera, it was pitched as a simple, tough camera safe to hand to children, with big controls and a friendly interface.
It is waterproof to 5m, shockproof from 1.2m drops and dustproof, built around a 10.1-megapixel 1/2.9-inch CCD and a 3x Zoom-Nikkor covering 29-87mm equivalent at f/3.3-5.9. It records 720p HD video, frames on a 2.7-inch 230,000-dot LCD, and is powered by Nikon's EN-EL12 lithium-ion battery.
Oversized buttons, simple menus and the sealed body make it a genuine beach, pool and playground camera for families and beginners; image quality is modest snapshot grade with ISO topping out at 1600, so it is not a low-light tool.
On used examples the waterproof door seals are the critical check — inspect the gaskets for grit, perishing or a door that no longer clicks firmly shut, and treat claimed water-resistance on a decade-old body with caution. Verify the EN-EL12 battery holds charge; replacements remain easy to find.