As you’re walking around, you’re sure to notice the overwhelming amount of turtle imagery on T-shirts, sun hats, and beach towels. That’s because Praia do Forte’s logo is the sea tortoise; in fact, one of the reason’s for the town’s success as a thriving eco-resort is the presence of Brazil’s acclaimed Projeto Tamar (an abbreviation of the Portuguese phrase for sea turtles: tartaruga marinha).

Founded in 1980 by the Brazilian Environmental Agency (IBAMA), this nonprofit organization studies and works to preserve the lives of the giant sea turtles living along Brazil’s Atlantic coast, which is home to five out of seven of the world’s sea turtle species. Until recently, many were facing extinction as a result of rampant overfishing and urbanization that destroyed nesting sites.

In Praia do Forte, Projeto Tamar’s mission is not only to save the turtles (and their eggs—traditionally a staple food for local fisherfolk), but to actively involve the population in their plight in a sustainable manner. This is done both directly (by patrolling the beach at night to move eggs or hatchlings at risk of being harmed), and indirectly (through increased tourism that the project has brought to the region).

Indeed, eggs, hatchlings, and turtles of all ages find refuge at the Tamar research station (tel. 71/3676-1045, www.tamar.com.br, 9 a.m.–7 p.m. daily, R$12), located on the beach just behind the pretty whitewashed Igreja de São Francisco. It’s filled with pools and aquariums where you can observe the turtles at various stages of their existence—from utterly cute, tiny hatchlings to gigantic full-grown creatures capable of living up to the ripe old age of 200. The center includes bilingual information and a gift shop selling the infamous turtle-themed paraphernalia (all proceeds go to Projeto Tamar). There’s also a shady café and restaurant on the premises.

Praia do Forte is also the headquarters of the recently opened Instituto Baleia Jubarte (Av. ACM 51, tel. 71/3676-1463, www.baleiajubarte.com.br), a research station for studying humpbacked whales. Between July and October, these 40-ton mammals trade the frigid waters of Antarctica for warm currents more conducive to reproductive activities. The institute organizes offshore boat trips (R$130 pp) led by resident biologists, which allow you to get a close-up glimpse at these fascinating giants.

Back on land, an important historical landmark is the Castelo Gárcia d’Ávila (tel. 71/3676-1073, 9 a.m.–6 p.m. Tues.–Sun., R$3). Originally a lowly clerk for the Portuguese monarchy, the ambitious Gárcia d’Ávila, as a reward for his services to the crown, received the capitânia of Bahia (which back in the 16th century embraced a large portion of the Brazilian Northeast stretching up to Maranhão). As a wealthy landowner, d’Ávila based himself in Praia do Forte, where he amassed more wealth by introducing cattle ranching and coconut palm plantations (and by cruelly exploiting slaves).

Built between 1551 and 1624 on a strategic hilltop overlooking the sea, his castle—now in ruins—is one of the first stone structures and the only medieval-style fortress in Brazil. The recently renovated Capela de Nossa Senhora da Conceição houses a tiny museum. The castle can be reached by walking along a 2.5-kilometer (1.5-mile) stretch of dirt road (known as Rua do Castelo) that branches off from the entrance to Praia do Forte.