In Akashi, Japan, the seaside HiPoPo PaPa restaurant boasts a rather unique bathroom. Longtime restaurant owner Koichi Miyanaga built this aquarium bathroom way back in the 1980s, though design firms all told him it was impossible.

According to Japanese newspaper The Asahi Shimbun, Koichi DIY'd it with a carpenter buddy and a glassworker buddy. It took them four tries to get it right (one of the early versions cracked under the water pressure). The bathroom, which is enclosed in a stainless steel frame and double panes of 18mm-thick tempered glass, cost a staggering $284,000 to build. The tank is filled with 300 tropical fish.

Cool as it is, the bathroom is staggeringly high-maintenance. Miyanaga, who's now in his 70s, spends an hour each morning cleaning the tank and filter, and his monthly water bill is ¥200,000 (USD $1,303).

Miyanaga only allows female patrons to use the bathroom—they're "cleaner users"—though they're allowed to show it to male companions with the door open.