She is a sperm whale in light blue coloring. Like all the whales, she has a blowhole on the top of her head. Her eyes are color dark blue. She has a pair of blue fins.
Thelma is very kind to Hercule and the puffins of Mossy Bay Island. However, she is always wise whenever someone asks for help.
Besides living in Mossy Bay Island, Thelma is also very good at transportation by bringing Hercule, Sidney and Snowbert across the glacier.
- The Story of Hercule Mustache (first appearance, no lines)
- The Story of the Puffins of Mossy Bay (last appearance, no lines)
- She, along with Gunnar, Alfie and Charlie, are the only characters that don't speak in Season 2.
- She is the second resident to appear in another region besides the zoo and her home. The first is Hercule Mustache.
- Thelma is based on a sperm whale.
- Thelma is the only animal that only lives on the water.
- She never spoke.
- Thelma does not have a mouth until Episode 36.