Jack and Annie did not expect the tree house to land on the ground instead of in a tree. The ground was pink. From reference books, they found out that it was a coral reef. It was made up of millions of coral skeletons.

Suddenly, Annie found a "mini-sub" on the seaside. Was it left by oceanographers? Or was it broken? Were technicians coming to repair it? Annie was curious to go inside and take a look. She also could not help pressing a few buttons on the computerized control panel. What happened then?