What's the best way to hide tattoos in summertime?

Basically the title, I've been looking for ways to hide my tattoos on my lower arms during summer but can't find a solution for everyday situations. I wear as much long sleeved shirts as possible but when it's 30°c out that really sucks.

My family is extremely religious, hates tattoos, and i see them every day, so I'd love any advice/ideas you may have.

What's the best (waterproof) way to hide them during summer?