CLOSED CONTAINER, LID UNIT, BUOY, AND UNDERWATER MONITORING DEVICE

To provide a closed container capable of suppressing a sudden increase in internal pressure.SOLUTION: An airtight container includes a container body having an opening formed therein, a lid unit that closes the opening, has a facing surface facing the outer surface of the peripheral edge of the opening of the container body, and is provided with a groove surrounding the opening formed in the facing surface, and an O-ring installed in the groove in an extended state. The groove includes a first portion on the side closer to the opening, and a second part deeper than the first portion on the side far from the opening. A first gap leading from the inside of the container body to the first portion and a second gap leading from the second portion to the outside of the container body are formed between the outer surface of the container body and the facing surface of the lid unit. The O-ring is retained in the first portion and closes the first gap, and when the internal pressure of the container body increases, the O-ring moves from the first portion to the second portion, thereby creating a gap between the outer surface of the container body and the O-ring.SELECTED DRAWING: Figure 11 【課題】内部気圧の急激な高まりを抑制することが可能な密閉容器を提供する。【解決手段】密閉容器は、開口が形成された容器本体と、容器本体の開口の周縁部の外面に対向する対向面を有し、対向面に開口を囲む溝が形成された、開口を塞ぐ蓋ユニットと、溝に伸長状態で装着されるＯリングと、を備え、溝は、開口に近い側にある第１の部分と、開口から遠い側にある、第１の部分よりも深い第２の部分と、を含み、容器本体の外面と蓋ユニットの対向面の間に、容器本体の内部から第１の部分に通じる第１の隙間と、第２の部分から容器本体の外部に通じる第２の隙間と、が形成され、Ｏリングは、第１の部分に保持されて第１の隙間を塞ぎ、容器本体の内部気圧が高まると、Ｏリングは第１の部分から第２の部分に移動し、容器本体の外面とＯリングの間に隙間が生じる。【選択図】図１１