Arugam Bay, but keep in mind monsoon seasons - best time to visit is April-October, Mirissa & Unawatuna - between November-April, Bentota is good for water sports (i.e. water skiing, snorkling, diving). Avoid beaches close to Colombo i.e. Mt Lavinia or Negombo & surrounding - they are dirty and so as the water in the Ocean.

arugam bay is realy nice.

hikkaduwa beach in the west coast, Negombo beach also nice.

It depends on what you are after. The Beaches around Arugam Bay can be quite steep if you want to walk but there are some excellent surf breaks. Crowds are not a problem if your are willing to take a short tuktuk ride north or south. The beaches around Colombo can be a bit dirty with rubish depending on how much rain they have had? Negombo fish markets are interesting but beach is well there are better! There are some lovely bays just south of Galle.

Mirissa beach and hikkaduwa. i think

I would suggest Mirissa beach all the way down on the southern tip a couple of hours after Galle. Lovely train ride.

Bentota Beach Resort

Hey Nils - I think Arugam Bay is getting known, but most people still don't venture to that part of the country when there are so many beaches closer to Colombo.

Bentota is very good. the beach is clean & so is the water. its safe & not very far from colombo. the taj bentota is a good option to stay & not really very expensive.

D.G.: Fun that you mention Arugam Bay. I thought is was stlll sort of undiscovered by visitirs..

Hey Carlos...the best beaches are a bit out of the way, on the east coast close to places like Arugam Bay or Trincomalee if it is accessible. Closer to Colombo I enjoyed Bentota..lots of watersports there as well. Negombo is too crowded IMO and rough seas. Same for Hambantota..it used to be good but after the Tsunami years ago its very rough waters there, even though the beach is great.