I swim at Asphalt Green sometimes. The masters practices are great. Send Coach Craig an email to ask about dropping in while you're in town.
AGUA masters
I've trained there several times on several visits to NYC
it's the only 50 meter pool in Manhattan
Asphalt Green Masters Team
The drop-in rate for USMS members is $20.
Bring your USMS card
Weekly Practice Schedule
M W F 5:45am - 7:15am
M - F Noon - 1:00pm
M - Th 7:30pm-8:30pm
Sat 6:00am - 8:00am*
I've trained there several times on several visits to NYC
it's the only 50 meter pool in Manhattan
Ande - there is another in Manhattan! Riverbank State Park is 50 Meters, and it only costs $3 or so to drop in during the morning.
nysparks.state.ny.us/.../fees-rates.aspx
It's where I got my start swimming before I moved upstate.