Ryugu Sea Cave is one of the most famous spots in Izu and part of the Fuji-Hakone-Izu National Park. It isn't anything particularly spectacular, but if you are in the area, you may as well visit.
An easy hike with some of the most amazing waterfalls you will see.
An underated hike out in the middle of nowhere in Nagano prefecture. Mind-blowing waterfalls and epic adventure over suspension bridges.
Mount Takao (高尾山, Takaosan) is one of the closest natural recreation areas to central Tokyo, offering beautiful scenery, an interesting temple and attractive hiking opportunities. Although outside the city center, the mountain is still located within metropolitan Tokyo and takes only 50 minutes and 390 yen to reach from Shinjuku.
Tataki falls is a stunning waterfall located in the southern section of Yanbaru National Park, home to rare and endangered animals endemic to Okinawa.
Walk through the ancient rainforest and soak in the sights. Tataki falls is one impressive waterfall.
In sleepy Iwamura there is a sign that self-proclaims itself to be the best rural landscape in all of Japan. It's a bold claim and one that I would personally disagree with, but nonetheless it exists. From the lookout you get a 360 view of farmland and ricefields. Something that you can see anywhere in Japan. Do not get your hopes up, just because it is apparently the best in Japan.
Tsukechi Gorge located in Nakatsugawa has unbelievably blue water and stunning waterfalls. The walk is very nice.
Yarigatake is one of the 100 famous mountains in Japan. It is located in the Northern Alps and is one of the most instantly recognisable peaks in Japan. It is the 5th tallest mountain in Japan, and is just awesome. A two day with a thrilling scramble. Being 3000m above sea level, things just hit different.