plughole

The water went down the plughole with a loud gurgle.

水发着响亮的汩汩声流下了排水洞。

Then, after a few fruitless minutes searching for the plughole, you discover that to drain the water away, the entire devicetips rotates around until its disk is tipping gently forwards.

再转过来，看到那个凹了吧，躺进去放上水，以洗一个泡泡浴了。