Lead Anchor

Evocation
Level: Alchemist* 2, Bard * 2, Druid * 2, Hunter * 2, Ranger * 2, Shaman * 2, Warlock * 2
Components: V, S, M (a bag of air), DF
Casting Time: 1 Standard Action
Range: touch
Target: creature touched
Duration: 10 minutes/level
Saving Throw: Will negates
Spell Resistance: yes
  The target's buoyancy becomes and stays swiftly sinking, regardless of how dense the target and its gear are. Among other effects, the target can walk on the bottom, but she also needs to succeed at a DC 20 Swim check to swim towards the surface and to stay above the bottom (see Buoyancy on page 43). This makes lead anchor a useful spell both for exploring the sea floor and for Drowning an air-breathing foe in the water.