Although Arthur “Tony” Islas typically applies his wilderness medicine expertise in treacherous outdoor environments, it came in handy far sooner than expected while on an airplane to South America.

Located about 62 miles off the western state of Nayarit, the Islas Marias became a prison in 1905 under dictator Porfirio Diaz and was in almost constant use until it was closed by Lopez Obrador in ...