Said to be the most active volcano on Honshu – Japan’s main island – Mt. Asama is one of the few mountains in the country that people are not allowed to climb. At 2568 metres above sea level, Asama broods at the southern end of the Joshinetsu Kogen National Park and is best experienced at Onioshidahi Volcanic Park.

The park is comprised of the Asama Volcano Museum – exhibiting information and displays about Mt Asama and the geography of volcanoes – and, most strikingly, an expansive natural ‘garden’ of immense boulders and rocks ejected from the volcano during its last major eruption in 1783.

Walking trails now meander between the boulders making-up both short and long walking circuits. Thriving within and on those boulders, countless varieties of rare and unique alpine plants grow in an other-worldly landscape. For further information regarding the many highlights of Karuizawa, please refer to our ’25 Things To Do In & Around Karuizawa’ page.

Mt. Asama is an active volcano and your personal safety should be your first priority. The Japan Meteorological Agency provides real-time advice and warnings for the entire country. Prior to visiting Asama/Onioshidashi Park, we recommend checking the following website.