An onsen (温泉) is a Japanese hot spring; the term also extends to cover the bathing facilities and traditional inns frequently situated around a hot spring.
Depend on the regional location, it had run by Japan traditional Ryokan (旅館 Japanese style inn) or by resort hotel. It can be enjoy in various way. For me personally I like to enjoy outdoor onsen with landscape scene that change follow the four season, spring, summer, autumn and winter. I personally found it enjoyable by simply sit and take the onsen bath by do nothing, just enjoy the scene and get calm. Always in my mind is sometime I thought travel so far, actually is come for enjoy the onsen and that moment of joy.
Hot spring used to be a sacred place where people can cure their injuries and diseases in earlier time when they had little knowledge of health and had little medication. In Edo period, people with disease started to stay for weeks or more at hot spring area to be cured and it was the start of the inns nowadays. Now Hot spring has become an entertainment in Japan include sightseeing tour.
For traveling kingdom of onsen, it hard for you will miss area famous for onsen, it just a matter of whether you are willing to make a stop and a stay. For me, when traveling Japan, I always will saw the area I pass by will had famous onsen town or Ryokan, maybe worth a stay instead of taken modern hotel accommodation. As far as travel experience in concern, onsen ryokan is in the first choice.
If you eating, make sure you pause for at least 30 minutes before taken onsen. Bathing can make it harder for muscles to relax and can place a greater burden on your heart.
I recall few of my personal enjoy moment to be share over here.
First trip to Japan, I choose to travel Hakkaido during winter time. One stop at Niseko, got indoor and outdoor onsen. After try out indoor, move toward outdoor. Since it is in the late winter, it is actually cool by moving your body from indoor naked till you had your body bathing inside the outdoor onsen pool. Then I can enjoy the scene just in front of me. Winter and slowing scene, as from what I saw is forest cover by winter slow, and the snowing happening, that what so beautiful for the landscape scene, never thought before can enjoy it in such a way. There after I had hold very positive experience with taken onsen. Off course, no all the stays along the trip is all had such a great landscape scene, but it matter of enjoy.
Trip 6 to Japan, while explore Shikoku and in Shadoshima island, the outdoor onsen is actually at the resort roof, so can take the opportunity to saw all the surrounding area.
Trip 7 to Japan, revisit Shirakawago, but this round is autumn (last round I visit is winter). And I choose to stay in the village onsen ryokan. It is enjoyable moment to take the outdoor onsen while see the autumn scene spread among the mountains and hills, hear the river stream and feel the breeze of winds. We can live our life in busy way or choose to be enjoy it in the right environment, context and right scene.