Pugwash is a mini-submarine who travels the world with Stewiacke taking underwater photos while he explores the coasts.
Pugwash dreams of being a brave explorer and photographing the ocean's depths herself, but now has to overcome her fears of foghorns and lighthouses. She also loves to wander off and explore things. She is also a busy, bustling little mini-sub, who enjoys hard work and hardly grumbles. Although susceptible (or suggestible) at times, she’s a kind mini-sub and always proves her worth by being a happy little worker. 
- She was originally going to be called Sophie.
- Her name comes from the village of Pugwash in Nova Scotia. The name 'Pugwash' itself is from the native Mi'kmaq word 'pagwe'ak' which means 'Deep Water'.
- A spin-off of Theodore Tugboat, which would've been called Pugwash's Underwater Adventures, was planned but never made.
- Pugwash's model was supposed to be on display at the Maritime Museum of the Atlantic, but was instead returned to Cochran Communications.
- In Pugwash's first appearance, she was seen without any underwater lights, but in later episodes she obtains them and are used throughout.
- She was named after the salting mining and fishing village of Pugwash in Nova Scotia and its river, which runs down to the Northumberland Strait.
- ERTL (bath toy; discontinued)