We did the 2 hour tour ( but it went for 4 hours!) . The first part is with the folks who booked the shorter tour, and then they leave half way and you get to go deeper into the lava tubes with the 2 hour tour. I would recommend the longer tour because you get to really go MUCH deeper into the caverns if you have time, but the short tour is fine if you want a shorter excursion. There were only 3 people on the longer tour ( all in our group) so it was like a private tour. The tour guide Moe was flexible and told us we he could tailor the tour to what we wanted ( we wanted to go deeper in the lava tube). Moe obviously LOVEs the lava tubes and shares all he can about the research that is being done there. He was very informative and went over and above with his time and expertise. If you want to do something less 'commercial' and more educational/cultural on the Big Island, check this tour out! It was more PBS and less Disney-like experience, but that was fine with me. Note: You must call and make reservations, this is on private property and not open to the general public . read more