If you haven't seen coral reefs, you haven't been to the Red Sea!
Be sure to visit coral reefs, and any, the main thing is that they are alive. I swam near them with a mask and snorkel daily while we were in Egypt. The feeling that you are swimming in an exotic aquarium and every time you see something new and unusual.
The most economical option is to choose a hotel near a coral reef, then all you need is a mask and snorkel.
A more expensive option is a boat trip with snorkeling (we swam on one, despite the fact that there was also a reef near our hotel, but we really liked it)
The most expensive is diving. We didn't go diving because we were with children, but if you're not afraid - go ahead!
An option for those who cannot swim is a bathyscaphe, or a boat with a transparent bottom, we rode our youngest son on it. How it was possible to see here
