This is part of an effort to build an artificial reef off the East Coast to create habitats for marine life and recreational fishing. The MTA steam cleans the subway cars and strips them down of components that float and decompose before dumping them in the ocean.
Photographer Stephen Mallon spent a couple of years after the start of the artificial reef program documenting the disposal of old subway cars. He has granted us permission to publish his stunning gallery here, also courtesy of Works Artists and The Front Room.