Yogis can stretch out alfresco at the Prospect Park Peristyle (enter at Parkside Ave and Prospect Park Southwest, Windsor Terrace, Brooklyn), where five different teachers will conduct hour-long classes in view of the Prospect Park lake. Choose among vinyasa (noon, 6pm), Kripalu (3pm), hatha (4:30pm) or a blend of yoga styles (1:30pm). The bucolic setting and inability to smell your neighbor should make for an extra-special practice. Go to springintoyoga.blogspot.com for more information.