There are undeveloped forest trails on Isla Colón [1] and other islands in the archipelago, but as usual only hike in the forest with a knowledgeable guide. Certainly don’t hike alone.
Be especially careful on any hike in the forests of Isla Popa, which still has fer-de-lance and other venomous snakes. (Isla Bastimentos [2] enjoys the best reputation among the snake-phobic; a species of nonaggressive coral snake with a mouth too small to be much threat to humans is the only known venomous snake on the island.)
Links:
[1] http://www.moon.com/destinations/panama/bocas-del-toro/isla-colon
[2] http://www.moon.com/destinations/panama/bocas-del-toro/isla-bastimentos