Panama Canal Fishing runs boats out of Gamboa onto Gatún Lake and the canal itself, which is an odd and good way to spend a morning: peacock bass in the drowned forest, container ships passing a few hundred metres away, and howler monkeys on the islands that were hilltops before the lake was made.
They also do deep-sea and fly-fishing trips and river runs, with transport from Panama City included on the main packages. Their site names one of their numbers as the WhatsApp line.