Master every organ in a level — pass its Easy and Medium quizzes — to unlock the next, more powerful submarine and dive deeper into the body!
Level 1 submarine
Your first mini-sub! Small and zippy — perfect for cruising the chest and meeting the heart and lungs.
Level 2 submarine
A sturdy sub built to ride the rivers of digestion through the stomach, liver and winding intestine.
Still to master: The Heart, The Lungs
Level 3 submarine
A clever sub with delicate sensors for the quiet, electric world of the brain and eyes.
Still to master: The Stomach, The Liver, The Small Intestine
Level 4 submarine
A fast, tough sub that races along the bones and powers through the busy muscles.
Still to master: The Brain, The Eyes
Level 5 submarine
The legendary deep-body explorer, built to dive into the filtering kidneys and the mighty skin.
Still to master: The Skeleton, The Muscles
💡 Tip: Submarines unlock by mastery, not points — pass every organ’s Easy + Medium quiz in a level (4/5 or better). Hard quizzes and perfect scores still earn bonus points for the leaderboard!