Is my Apple Watch series 4 waterproof?

Is my Apple Watch Series 4 waterproof? I see these swimming apps on the App Store and get I have never heard about, or thought about whether they are waterproof or not? Or water resistant enough to go for a swim in a saltwater pool? At my gym there are both salt water and chlorine pools. I have been wanting to make a regular thing of working out in the saltwater pools since chlorine exposure (especially repeatedly over time) is not good for the human body. However, I know how toxic salt water is for electronics.

This is reminding me to double check the status of my Apple Care and read the fine print.