We highly recommend you book in advance in order to guarantee a place for the hour you want. We do accept walk-ins as long as there is space, but space is limited on each tour so we cannot guarantee it is available unless you book ahead. For groups it is especially important to book ahead as it’s unlikely we will fit a large group on a tour if they just show up. You can see the availability here on our website or call us to check if you have a specific time in mind. The standard tour runs every hour on the hour and sometimes on the half hour during the busy seasons. For the Lava Falls Adventure tour you need to book at least 1 day in advance.