There are plenty of decent tablets on the market. Not all of them are waterproof though. The Nite Ize Runoff Waterproof Tablet Case has you covered. It protects your iPad Pro and Microsoft Surface Go from water damage. The case is touchscreen friendly, so you can interact with your tablet through the transparent window.
This tablet case has a waterproof rating of IP67, so it can be submersed in 1 meter of water for up to 30 minutes. This waterproof tablet case is available for under $50.