John is an expert on rainforests and does walking tours at whatever level you want. I found him on Cruise Critic and he has some reviews here on TA. He will pick you up in SJU or meet you closer to the forest. His commentary really helped us understand the intricate systems at work in this massive forest and while it is not cheap we felt it was worth the investment. He can be reached at 787 309 6224 OR email at email@example.com. This is not an ad...we used him 2 weeks ago.