Driving 30 km east of Baracoa, past a mountainous stretch of Cuba's La Farola highway and the tranquil waters of Mata Bay, you'll come across another one of the country's numerous unsung natural wonders: the Yumurí Canyon. This lush, tropical gorge is an unexpectedly impressive sight to say the least, with walls at points measuring nearly 200 m from the canyon floor. Its eponymous river, dotted with deep natural swimming pools, is neither deep nor particularly fast flowing, making it ideal for exploring the near-complete seclusion of eastern Cuba either via rowboat or on foot.
Speaking of exploring, you'll have a few options available to you ranging from half-day canyon rim hikes that traverse both the upper and lower sections of the gorge to boat rides up the river itself, which almost always include stopovers for hiking/swimming. You'll find access to all of these excursions, the local guides who lead them, as well as to the canyon itself from the small fishing village of Boca de Yumurí, which is situated on Cuba's Atlantic coastline just southeast of Baracoa. Simply show up and let the local economy do the rest. When you're done adventuring, grab a drink on a nearby beach and congratulate yourself on having experienced a beautiful slice of "authentic" Cuba.
Note:Try to avoid buying the colorful Polymita snails which will inevitably be shoved in front of you at some point during your visit. They've been harvested to near-depletion in recent years to satisfy the trivial curiosities of tourists, so it's best not to contribute to the problem.