City Treehouse
129A W. 20th St., nr. Sixth Ave.; 212-255-2050; from $12.50 an hour for members, $30 an hour for nonmembers; first visit is free if you register here.
The main draw of this newly opened playroom is the extra-long tiered water table with fountains and whirlpool, tanks that fill and empty at the turn of a knob, and plenty of balls to bob and animal toys to bathe. There are "yuck buckets" for toys that end up in mouths.