It was three days at sea aboard the Hiva Oa and one of the biggest surprises in the professional lives of three divers with decades of experience at sea.
The crew, made up of molecular biologist Mauro Rebelo, diver and cameraman Leo Francini and myself, a documentary maker and navigator, set off in light winds from the Píer de São Francisco, in the city of São Sebastião, towards the Alcatrazes Archipelago, some 50 kilometers away.
The insular group of five larger islands has been protected since 2016 within the limits of the Alcatrazes Wildlife Refuge, administered by ICMbio. This important marine conservation unit was the result of civil society movements to stop military weapons testing at the site by the Navy, which had controlled the area since 1930. Under the current law, only one of the islands, Sapata, can still be used as a target for Navy guns, and all the others are protected from this activity.
After five hours of smooth sailing and motoring, the three of them were ready for their first dive at Farol Island, the only island with a maritime beacon, which is currently deactivated.
The appearance of the water from the deck seemed unusual and had already intrigued everyone on board. But the surprise was only fully revealed when the three of them jumped out of the sailboat and opened their eyes, protected by their diving masks: in the water they could see nothing but a completely red mass.
The normally blue-green sea in that place, with its good transparency, looked like a muddy river. Everything indicated the presence of a phenomenon known as red tide, when a marine area is affected by the overproliferation of red-pigmented microalgae .
Despite the total lack of visibility, the divers decided to go down with their sun coral collection equipment and their underwater photo and video cameras. They agreed to maintain close eye contact, as the field of vision was restricted to about half a meter. Everything beyond that distance disappeared from view.
It was something like diving into beet soup. What's worse, not even the light could penetrate the opaque liquid and at a depth of 2 meters it was already dark. We could no longer see anything, not even the reddish color of the water, just darkness.
At a depth of 3 meters, another unusual development: the red water gave way to very clear water, as is common in the area, and the almost zero visibility went down to about 12 meters, a distance that the three divers could only see by using their flashlights to illuminate the bottom as dark as on a moonless night.
Another unsuspected factor present on this unusual day: the thermocline, the transition zone between the warm surface water and the cold, deep currents of the Atlantic, began much shallower than normal. At a depth of 6 meters, the water went from 23 degrees to around 17 degrees, very cold even for bodies protected by a 7 millimeter layer of neoprene.
The unusual conditions didn't stop Mauro from collecting. And it was all documented in photography and video by Luciano and Leo. This material can be seen in the galleries on this page.
The next day, we set off early from Alcatrazes for Búzios Island, the second largest in the Ilhabela Archipelago behind the large island of São Sebastião. The 50-kilometer, five-hour journey was made entirely by motor in a complete calm of wind and sea.
The two dives in Búzios revealed a condition in no way reminiscent of the day before: blue and very clear waters with no sign of the dense tide that brought night to the Alcatrazes seabed at two o'clock in the afternoon. In addition, the divers were struck by the density of occupation of the sun coral, with vast areas of the bottom rocks completely covered by Tubastrea mats, as can be seen in the image galleries opposite.
It is interesting to note that in Alcatrazes there has been a program to remove invasive corals for two years, while on the island of Búzios there has never been any control of the species.
After a night sheltered in Saco do Sombrio, on the east side of Ilhabela, Hiva Oa sailed back to the starting point carrying samples and images of amazing days.
Luciano Candisani
