Description:

Map of northwest Africa by celebrated French geographer Guillaume de l'Isle (1675-1726), the father of modern cartography and a member of the French Royal Academy of Sciences. This highly detailed map, annotated in a somewhat amusing manner (at least when read from a contemporary perspective), was engraved by Inselin and describes the Niger river as an offshoot of the Nile.
The Sargasso Sea is located just off the coast of Africa. An enormous lake joins Senegal and Niger, and so it goes on.
Some of the more delightful annotations are worth a quick detour:

• "Kingdom of Temian, the inhabitants of which are what are referred to as Anthropophagi."
• "The Calbongos Peoples, mean-spirited and deceitful, and the enemy of their neighbours, the other Calbongos."
• "Desert of Berdoa, a great Dry Place, where there is no Safety for merchants due to the bandits."
• "This area is said by some to be the location of the fabulous island of St Borondon."
  

A description of the Canary Islands is accompanied by a description of the island of San Borondon, the mythical isle discovered by Saint Brendan (or Brandan ), the great Celtic navigator, at the end of his celebrated travels to the Fortune Islands. The island of San Borondon was paradise on earth.
Please note that Prospero's island would be found in the upper right-hand part of the chart.

Note:

Saint Brendan (ca 486-550), an Irish monk and a priest in Clonfert, undertook a series of maritime adventures in the first half of the 6th century that took him to Greenland, Iceland and probably the Americas (well before Columbus) in search of paradise on earth.
The description of an island discovered by the priest and on which he celebrated mass before it disappeared under the waves is sometimes confused with the final stage of this sailor's journey. An island cloaked in fog and on which an angel revealed to him the face of god before thwarting his attempts - for the soul alone may enter heaven after the body has disappeared.
Over the following centuries, especially during the 18th century, hundreds of witnesses claimed to have seen the eighth Canary Island - now known as the Ghost Island.

Following the acquisition of this map and numerous discussions amongst the staff of the Surnateum in 1938, an expedition set out to find these islands.
The explorers were not necessarily looking for heaven on earth, but they did assume that the island would be a gateway to Atlantis - or the remnants of Atlantis. According to one theory, the Canary Islands were the visible part of that lost continent, as described in Plato's Timaeus.
This did not necessarily contradict the theories expounded by Ignatius Donnelly (1831-1901), an American who, in 1882, published his work entitled Atlantis, the Antediluvian World. Recent work by German archaeologist Leo Frobenius also moved in this direction (Mythology of Atlantis).
A discussion with Professor Auguste Piccard on the possibility of building a device allowing man to explore the ocean depths has convinced our archaeologists of the value of promoting research in this area. Some sensitives had expressed the hypothesis - typical of that time - that they were descendants of the people of Atlantis. They were trying - and indeed they still are trying - to find a reason  to explain their curious gifts.
The Collector did not share this opinion and so advised against the trip. Certain Nazis also thought they were descended from the people of Atlantis, and the Collector had no time for their regime. Moreover, the Collector was more interested in returning hauntiques to their rightful place, not removing them from their natural environment or sanctuaries. Too many unscrupulous individuals had already committed irreparable acts of sacrilege.
Despite his pleas for restraint, a small group set off for the Canary Islands on a voyage of discovery.
As they have never been heard of since, we can only suppose that they found the island - or that their ship went down with all hands.