I have always loved the Aquastar benthos range, and have owned quite a few over the years. Proper diving watches with a unique one hour timer complication, controlling a large orange hand started from a single pusher. They are attractive watches with strong ties to Omega. I believe Omega have credited Aquastar with the ideas for the designs of their diving watches, and Tissot was one of the brands used on the dial along with Lemania.
They are very well made, the quality is up there with Omegas of the day, with large stainless steel cases, screw down crowns and acrylic(or metal on the earlier versions)bezel inserts and with an A Schild auto movement. Screw back cases with the star logo cast into the case back.
The Benthos, which refers to things found on the ocean floor is rated to 500m and its successor, the Benthos 1, was substantially redesigned to be rated to 1000m using a mono bloc case.
This version has a very rare and unusual Decomp bezel that I have seen only one or two examples of