There are many volunteer organizations that accept advance bookings through tourism associations, but there recently are also those such as the 'Beppu Hatto Walk' of the Beppu-onsen Hot Spring area that allow anyone who assembles at a given place at a certain date and time to participate.
観光協会等の団体を通じた事前申込制としているボランティア組織が多いが、別府温泉の「別府八湯ウォーク」のように、決まった日時に集合すれば誰でも参加できる形態を採るところも最近ではある。