Coastal scientist Stephen P. Leatherman, director of Florida International University’s Laboratory for Coastal Research and known as “Dr. Beach,” announced his 21st annual Top 10 Beaches list on May 27. He has compiled the list annually since 1991 using 50 criteria. Here are his top 10 picks for 2011.Siesta Beach in Sarasota boasts that it has the finest and whitest sand in the world, and I cannot argue with this claim; the powdery sand is nearly pure quartz crystal,” Leatherman said. The water is blue, clean and clear, making it particularly inviting to bathers and swimmers.The beach is hundreds of yards wide, attracting volleyball players, beachcombers and sun worshippers. Waves are normally measured in inches, and the beach gradually slopes into the waters of the Gulf of Mexico, making it a safe area for children.This beach park is complete with showers and bathrooms, snack bars, grills, picnic tables, shade trees and a large parking area, which fills up on summer weekends. Siesta Beach is a smokeless beach, earning extra points for cleanliness and environmental management.“My favorite time to visit is after Labor Day when things have calmed down, and the water is still warm enough for swimming until November,” Leatherman said. “Snowbirds from northern climes call this area home during the winter because of the great weather. The beaches are for exploring, but not swimming at this time of year, albeit I have been in the water as early as March.”Fans of Dr. Beach will note that Siesta Beach was on last year’s Top 10 list in spite of the BP oil spill. “Siesta Beach in Sarasota was on the list in 2010 because I strongly believed that the Loop Current would keep any oil away from the southwest Florida beaches, which it did — my prediction was correct,” Leatherman said.Slide show text by Robin Dalmas, Bing Travel; photo editing by Connie Ricca.