A very interesting trip allowing visitors to see a variety of islands, reefs, arches and most notably the sea caves hewn into the reddish cliff. The Furado Grande is a marine tunnel (70m) long which opens out onto a small creek (Cova do Sonho), looked down on by high red granite walls. Under the fortress, a marine grotto (the Gruta Azul, the "blue grotto") has a strange emerald colour due to the refraction of light in the water.