Six of us are bunched together in a small blue boat, enjoying a cool breeze under the relentless Venezuelan sun. A maze of islands surrounds us, little green gumdrops whose reddish-brown shores slope steeply into forested interiors. Powered by a moody Yamaha motor, we chug our way toward Chiguire Island, a smidge of dry land named after the giant aquatic rodents that hang out there.