Chuen Kee Seafood Restaurant is one of the two large establishments along the Sai Kung Promenade, along with Hung Kee Seafood Restaurant. There are several others in the area to choose from but this is one of the two big boys with large outdoor dining area and loads of tables, usually quite full.
As other posters have commented, you are first seated then taken to the large tank area to select which fresh seafood you want. The restaurant is quite distinguishable not only because of the large neon fish sign which also reads Chuen Kee Seafood Restaurant but also because of the very large fish tanks you can see in front of the restaurant. As staff speak very little (or not) English it can be a bit difficult ordering if you are not with a Cantonese speaker.
For those interested in this type of dining experience, it is worth nothing that the Sai Kung seafood scene has a long standing reputation of being very expensive compared to other Seafood Restaurant hot spots in Hong Kong like Lamma Island or even many Seafood restaurants located in the city. Also, there have long been rumors of ingredient (and even seafood) switching, tiered pricing for locals and visitors and bouts of poor food quality at some of these restaurants. We have had better luck with Chuen Kee than others on the promenade but its still worth checking the local food review website, called open.rice to read up on the various restaurants serving seafood in Sai Kung before making your decision which to try.
Chuen Kee Seafood Restaurant is past Hung Kee Seafood Restaurant if you are walking along the Sai Kung Promenade away from the main piers and bus depot area.