Though hotels are all similar in that they all have beds and other accommodations to make staying there much more homelike, there are some very unusual hotels in various parts of the world that challenge the concept of the traditional hotel.
There are treetop hotels in Costa Rica, Kenya and other parts of the world where the hotels are built with very large living trees making up a substantial part of the hotel structure. The Ariau Towers in Brazil, near the city of Manaus is in the middle of the Amazon on the Rio Negro and is a similar type of living tree hotel. Bill gates invested in the hotel and had modern telephone / internet connections installed.
Straight out of Neromancer, but only for the Japanese as of yet, capsule hotels are an economy type of hotel with extremely high occupancy density capabilities. Most capsule hotel compartments are only about 2 meters by 1.25 meters by 1 meter. This amount of space certainly gives one enough room to read or sleep, but not much else. Of course if you’ve got wireless internet the possibilities are considerably expanded.
Capsule hotels are not necessarily frequented primarily by lower income people, but are used by many types of people for many different reasons. For about $25-34 USD per night, a tired working person who stayed out too late drinking and missed the last train can get a night’s rest. There are often discount rates for those wishing to nap for only a couple of hours during the day.
There are several cave hotels throughout the world in such places as Australia, Spain, Turkey, the United States and several other countries. Rooms in cave hotels typically have the entire walls or even two or three walls made out of the mountain or other hard sediment formation that the hotel is built into.
There is one underwater hotel in the entire world that can be reached without the aid of scuba gear. The Utter Inn located in Lake Malaren, Sweden features one large room and visitors can simply walk down into the hotel while viewing underwater. This same company also has an undersea lodge in Key Largo Florida that does require scuba diving to reach.