Several options. For subways, the 4, 5, or 6 to 59th St gets you to 59th and Lexington. From there it's a few blocks walk(east) to the tram. Likewise, the N, R, or W will also get you to essentially the same spot. If you want to take the trip in reverse, you could take the F train to Roosevelt Island, which lets you off at the tram station on the island. For more info, check out the MTA's website (can't post the address, but it's mta, followed by info instead of the usual.
The answer below says it all
The nearest subway station is a very few minutes walk away.
Lexington Ave/59th Street station. N, R or W train.
The subway at 59th street is closest. We were staying in the upper west side so took the crosstown bus from 86th street through Central Park to the east side. You can use your metro card on the busses and also the island tramway.
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