We were on the BI a month ago and drove to the lava fields from Waikoloa. It was the highlight of our trip. Don't be discouraged about the length. As Eric mentioned, there is a whole industry at the end of the road catering to those hiking or riding in. I would highly recommend renting a bike and riding there. My DW and I actually took the "shuttle" as far as we could and then biked. Not strenuous at all. A fun experience. We were actually a little disappointed at the ocean entry because the viewing area is quite far away and you can only see very little of the actual lava entry. BUT, then you hike another 15-20 minutes up the lava field towards the mountain, to where the lava is flowing there, and it was amazing. This was worth the whole trip. Lava oozing and flowing, with nothing "roped off". You go as close as you dare, very very cool! I would very highly recommend doing the bike ride to the lava!