A shallow bath in a bathhouse or hot spring where you can lie down and relax. Often found in onsen facilities.
See also: 寝湯
I relaxed and gazed at the stars in the lie-down bath at the inn.
Standard kanji spelling.
Variant spelling using okurigana ころび instead of 転び.
Compound of 寝転び (nekorobi, 'lying down') + 湯 (yu, 'hot water, bath').