Walter Tremenheere was born in Penzance, the third son of a successful Penzance lawyer. He went to school in Truro. In 1779 he was commissioned in the Corps of Marines (later Royal Marines). He appears to have had training in drawing as a naval officer and two of his drawings were used by Nicholas Pocock (1740-1821) in The Naval Chronicle (Vol. 1, Plate XI and Vol. 3, Plate XXXV). He married Frances Apperley of Gloucester in 1802 and they had four sons and two daughters. After successful service at sea, he was placed on the permanent staff of the Royal Marines, Woolwich Division in 1805, eventually reaching the rank of General. He and his family were regular visitors to Penzance, where his brother, Captain Henry Pendarves TREMENHEERE, lived.
Walter Tremenheere died in London.