Wipe the drive, then start over... if this happens repeatedly, then start thinking about getting a new machine, as the water might have done damage to the motherboard, ATA controller, hard drive, memory, etc. (Ordinarily I would say repair it, since it's a Pismo-- and I'm typing this from my own now, but... it's getting long enough in the tooth, that a hardware problem that is unclear in what it is, is not worth repairing-- but rather just replacing the machine.)
Freya says, 'Hello from NOLA, baby!' (Laissez bon temps rouler!)