There are no other customers at the public bath in the middle of the night, so it's super relaxing.
It's nice to go to the public bath late at night because I'm the only one there.
ーThere are no other customers at the public bath in the middle of the night, so it's super relaxing.
「深夜銭湯に他のお客さんがいないので、とても快適です」
public bath で「銭湯」
in the middle of the night で「深夜に」
この場合の「快適」は relaxing を使って言うと良いでしょう。
ーIt's nice to go to the public bath late at night because I'm the only one there.
「自分だけしかいないので、深夜に銭湯に行くのは快適だ」
lt's nice to go to the public bath で「銭湯に行くのは快適だ」とも言えます。
late at night で「深夜・夜分遅く」
ご参考まで！
カナダ 
