There's a snorkeling spot along the reef running from Saba east toward Oil Nut....called "Jardines de Coral" on my chart. We were there a couple days ago before the big swells started. There is also a reef on the north side of Eustatia Sound running west from Eustatia Is that is good for snorkeling. They can be accessed via dinghy from the Saba anchorage or you can anchor your boat pretty close in calm seas.