Inquisitive (Colombo)

I'm coming to Sri Lanka from cool Canada to visit for three months starting in Jan. Protected content . Interested in places to stay especially near beach areas, where one can snorkel and enjoy the warmth. I will be traveling through SL to see the sites, enjoy the history and culture and would like to make a home base of a quiet beach area. Bar scene not important. Nice local restaurants a must.
Any suggestions appreciated.
Marilyn