Endurance swimmer Diana Nyad will swim for 48 hours in a special New York City pool to benefit the victims of Hurricane Sandy.

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(NBC-New York City) Swimmer Diana Nyad is getting ready for another endurance event. This one in the Big Apple.

Nyad will swim for 48 continuous hours in New York City's iconic Herald Square in a special pool that has been built just for the swim.

It'll all benefit hurricane Sandy victims. Celebrity swimmers and guest swimmers will also jump in the pool and swim a few laps with Nyad. The guests include Olympian Ryan Lochte, fitness legend Richard Simmons, New York firefighters, as well as Sandy victims.

The 48-hour swim for relief started at 8:40 Tuesday morning.