Sharing the Garvel Drydock with JUPITER was Argyll Workboats' SEAHORSE II. Now described as a "fully equipped offshore survey and combat weapons trials support vessel", she was built in 1972 as the Norwegian ferry SESSØY, and owned by Troms Fylkes Dampskibsselskap AS (TFDS), Tromsø. She was sold in 1987 and renamed SESSÖ by Swedish owners. Sold again, she came to British waters in 2005 and gained her present name. She is 144 gross tons, and 25.35 metres long. As built, she could carry up to 60 passengers and four cars. Nowadays, her passenger accommodation is used as a conference room. Recently she has worked with the Type 45 destroyer DARING while she was on trials.