As mentioned in this review of the Panama Canal, do not miss out on Barro Colorado! Only about 8 tourists are allowed on the island every day, so you must make your reservations in advance. Go to the website mentioned (http://www.stri.org/english/visit_us/barro_colorado/) for information on getting your reservations. You will not be sorry! The day I was there, we saw many howler monkeys, an anteater, many beautiful birds, lizards, butterflies, and so on. Our guide was very knowledgeable, interesting, and patient. Well worth the cost and the pre-planning required.