During September, Chelsea Piers will be offering free ice-skating lessons and general skating at Sky Rink for all ages on two Saturdays, Sept. 18 and 25. There will be free, 30-minute lessons at 1 p.m. and 2 p.m., and free general skating from 1-2:30 p.m. Sky Rink is located at Chelsea Piers at 18th St. and the Hudson River. To skate is free but skate rentals are an additional cost, $6.