Whilst in Egypt we just had to spend some time in the sea and we were not disappointed!
We did a little bit of scuba diving and a lot of snorkeling and I must say, The Red Sea is unbelievable for under water visibility but also the sheer amount of fish and sealife is just amazing. You can see from this photo that there are just things to see EVERYWHERE! If you are interested to know more about the types of creatures you will find underwater there is a great guide here.
To take our underwater and shallow diving photos we mostly used a Griffin Survivor Plus Catalyst Waterproof Case on an iPhone 5 and found it really reliable and fun! The pressure of the water mostly makes the touch screen unusable but if you enter the camera function before you go into the water then use the volume button to take photos it works fine! When we went deeper than 5m we used a Cannon Powershot which was a little trickier to use (mostly getting the white balance correct) when under the water. You can find a useful list of underwater cameras here.
If you ever get a chance to go near The Red Sea I would very much recommend taking the time to adventure into the water, it's a magical experience!