Our house in Japan really was built over a koy pond like this! We had a huge, 8 inch thick piece a glass for viewing, right in the middle of the living room floor. This one is from Kenrokuen, Kanazawa, Japan.
Another example of a pool / spa blending into the environment.Satonoyu Ryokan, Kurokawa Onsen Area, Kumamoto-ken (Kyushu) - Absolutely inviting, comfortable and well taken care of; stunning outdoor onsens await you here!
Not all of these are healthy substitutes in my opinion, but some are, so use your own judgement. 20 Unique Healthy Food Alternatives --I'm interested to read about some of these things, and I know some of the substitutions only work in some circumstances.