Joetsu City Marine Museum "Umigatari," which celebrates its 8th anniversary on June 26, 2026, is launching a new event starting June 15, 2026 — a special diver commentary session called "Kobdiver!" The event gives visitors a chance to learn more about the Kobudai, one of the signature fish in the aquarium's large tank that recreates the Sea of Japan.
Special Diver Commentary: "Kobdiver!"
Starting Monday, June 15, 2026, Umigatari is introducing "Kobdiver!" — a session in which aquarium staff explain the ecology and abilities of the Kobudai while divers interact with the fish inside the tank.
The Kobudai (Semicossyphus reticulatus) is recognizable by its reddish body, and in males, a distinctly large forehead hump and prominent jaw. The species is protogynous hermaphrodite: individuals begin life as females and transition to males as they grow larger. Breeding season is in spring, when males and females spiral upward near the water's surface to spawn. Their diet includes abalone, oysters, and crabs, which they crack open with their powerful teeth.
In the waters off Sado, the Kobudai has been a favorite with divers for years thanks to its distinctive appearance and its habit of swimming right up to people. At Umigatari, the fish has even inspired its own line of original merchandise.
During "Kobdiver!" sessions, visitors can watch the Kobudai swim around the divers and feed, while staff provide commentary on the fish's biology and behavior.
Event details:
- Period: Starting June 15, 2026 (Monday)
- Time: From 12:15 PM, approximately 10 minutes
- Location: 2nd floor, Umigatari Tube
New Explanation Panels Added to the Umigatari Large Tank
Umigatari is also adding new interpretive panels near its main tank to help visitors appreciate its distinctive structure. The "Umigatari Large Tank" is a diorama tank recreating the seafloor topography of the Sea of Japan at 1/10,000 scale — a complex structure not found at other aquariums. The new panels use a quiz format to introduce the features of this unique tank.
Panel details:
- Period: Starting June 15, 2026 (Monday)
- Location: Umigatari Large Tank slope area
