This page of our guide to Psychonauts 2 lists the Half-A-Minds available in Bob's Bottles.
You can find 2 Half-A-Minds in this level.
Location Bob's Island.
You will find this secret behind big rocks, on a small island.
Location: Viking Reception.
Getting to this secret requires a little dexterity. You need to jump onto the ship. First, you have to climb the thoughts to the very top, then jump on the paddles, and finally on the ropes on the ship's side.