Going on holiday to Bermuda, which beaches are best for snorkeling? any self catering suggestions?

I like Horseshoe Bay as well but depending on where you are staying it may be a bit far. Tobacco Bay and Ft. St. Cathryne beach are also great east locations. Here is what Frommers said:

The best places to go snorkeling are public beaches. Many hotels that are right on the beach will lend or rent you fins, masks, and snorkels, and will advise you of the best sites in your area. You almost never have to travel far.

Die-hard snorkelers, some of whom visit Bermuda every year, prefer Church Bay above all other snorkeling spots on Bermuda. It lies on the south shore, west of the Fairmont Southampton Golf Club and Gibbs Hill Lighthouse. The little cove, which seems to be waiting for a movie camera, is carved out of coral cliffs. It's well protected and filled with snug little nooks. Another advantage is that the reefs are fairly close to land. However, the seas can be rough (as is true anywhere in Bermuda), so we always advise caution.

At the eastern end of the south shore, John Smith's Bay, east of Spittal Pond Nature Reserve and Watch Hill Park, is another top spot, especially if your hotel is nearby. Even more convenient, especially for snorkelers staying at St. George or at a hotel near the airport, is Tobacco Bay, north of St. George's Golf Club. Another good small snorkeling spot is West Whale Bay; it lies along the south shore at the west end of Southampton, west of the Port Royal Golf Course.

Although snorkeling is a year-round pursuit, it's best from May to October. Snorkelers usually wear wet suits in winter, when the water temperature dips into the 60s. The waters of the Atlantic, which can be tempestuous at any time of the year, can be especially rough in winter.

Some of the best snorkeling sites are accessible only by boat. If you want to head out on your own, and you have a knowledge of Bermuda's waters, we suggest renting a small boat, some of which have glass bottoms. If you rent a boat, the rental company will advise you on where to go and not to go. Countless wrecked boats lie on the many reefs that surround Bermuda. If you're not familiar with Bermuda's waters, you should stay in the sounds, harbors, and bays, especially in Castle Harbour and Harrington Sound. If you want to visit the reefs, it's better and easier to take one of the snorkeling cruises recommended than to captain your own boat.

Horseshoe Bay is the most beautiful beach on the island.

remember Bermuda is the same latitude as South Carolina.....it is NOT the Caribbean ( St Thomas is the closest Caribbean island and it's 720 miles away!) so wear your wet suit!