From Bulbapedia, the community-driven Pokémon encyclopedia.
Old Shore Wharf (Japanese: カントー波止場 Kantō Wharf) is a dock in Kanto. It appeared in Mewtwo Strikes Back. Miranda works here as a pier master.
In the movie, Ash, Misty and Brock got an invitation from a Dragonite. The invitation included a hologram of a Nurse Joy, hypnotised by Mewtwo, who told them that Mewtwo was waiting for them on New Island and they would be able to reach it from Old Shore Wharf.
When they arrived at Old Shore Wharf, they were told that the boats to New Island wouldn't leave, because of the stormy weather conditions (which were caused by Mewtwo).