There's a ramp that goes up to Riverside Blvd at Pier I at 68th St. There's a staircase that leads up to the Eleanor Roosevelt Statue and 72nd Street right after that, and several park paths that circle around the men's room that also lead up to that entrance.

You can go through or around the rotunda at the 79th Street Boat Basin, climb that hill and catch the 79th Street traffic circle, or take the long ramp around 82nd, on the other side of the tunnel, just before Riverwalk. Then there's another tunnel just after Riverwalk. In fact, just about any path leading away from the river will eventually lead up to Riverside Drive.