Today we explored by hiking my favorite place in the Gulf of California, San Esteban Island. It is a highlight because it’s a natural laboratory of evolution that has produced two of the most amazing creatures: the spiny-tailed iguana and the piebald chuckwalla. Both animals are endemic but introduced to other islands, reputedly by the indigenous Seri. After thousands of years of isolation, they evolved into the interesting creatures we now know. Their behavior is awesome, with the spiny-tailed iguana (or ctenosaur, derived from its scientific genus, Ctenosaura) climbs to the cardon cacti’s tops to feed on the flowers and fruits, while the chuckwalla gets leaves, flowers, and fruits of diverse low desert plants at their reach. Our guests and naturalists walked on the wide and green arroyo and found these and other fascinating creatures, including endemic plants. It could not have been a better day!