Dive into adventure in the last unknown territory on Earth - the sea. Join Robby Hoenig and a cast of characters as unusual as any ever met on a distant planet... In the first Robby Hoenig adventure, Secret Under the Sea, an aquatic visitor from another world is threatened by a criminal gang... Gordon R. Dickson's Robby Hoenig adventures are timeless young adult stories in the tradition of Arthur C. Clarke's Dolphin Island.