Locke says that Claire & Kate are not candidates, the smoke can't cross water

At the camp, Locke asks Sayid if he can swim and tells him to wrap a gun in plastic.

Locke asks Claire what is wrong because she is nervously watching them. She asks if her name is on the wall of the cave, but Locke says it's not, but says that he does need her. He tells her that Kate's name is not on the wall anymore, but he needs Kate to convince the three other people he needs to leave the island. He says that once Kate fulfills her purposes, then "whatever happens, happens," implying that Claire can do what she wants with her.

As Sayid and Locke prepare to leave for Hydra island, Sawyer questions them, and asks why Locke can't just turn into smoke and fly to other island. Locke says that if he could do that, he wouldn't be on the island. He says that he's going to Hydra island to get Jin back.