An orphaned gosling adopted by Roz, representing the bond between technology and nature. Throughout the series, he matures and assumes a leadership role among the island creatures, exemplifying growth and the cycle of life.

Known as the "Ancient Shark," Gurry dwells in the Arctic region and possesses wisdom that Roz seeks to tackle the issue of the poison tide. This mythical shark, embodying resilience and survival, aids Roz in understanding the broader implications of environmental threats.

The manager of a mining station responsible for the poison tide, Akiko is a partner to Leo Larson and a mother, representing the human side of the story. Her interactions with Roz highlight themes of human responsibility and the tensions between technology and nature.

A powerful crab-like robot used for underwater mining operations, symbolizing the relentless pursuit of industrial goals at the environment's expense. Crusher's unyielding nature and immense strength pose significant challenges to Roz in her quest to protect the island.