On Upolo I would recomend Lalomanu on the Aliepata coast. There is a healthy coralreef along the beach with lots of magnificent marine life. Just keep on the inside of where waves are breaking. I still keep thinking of this as one of my best snorkeling experiences.
I also snorkeled at the Pololo Deep just outside Apia, but i thought that was disapointing, vith lots of currents and dead corrals, and it was a bit to swim to get to the deep part. The beach is not especialy nice, and you have to pay customsfee to enter.
I checked with my Lonely Planet wich said that Aleipata area offered the best snorkeling, and that there was not that many good spots on Sawaii.
Be smart and bring your own snorkeling gear, and a waterproof camera.









