Concessions of land in Ile Royale were supposed to measure no more than 40 toises in depth. Vallée, in making a survey of the harbour in 1734, noted that this regulation had been ignored in granting most of the harbour properties. Instead, up to 100 toises was granted to compensate the inhabitants for the poor quality of the land. [54] Though not suitable for cultivation, the land around the harbour was capable of producing hay fields and pasturage. [55] The most significant difference between the fortress-fauxbourg area and the rest of the harbour was the absence in the other four "zones" of significant marshland. The area behind the hills to the rear of the Royal Battery is described as a dried-up lake in the plans and may have been soft, wet ground. There are many other wet areas, but there is nothing to compare with the bog formations before the landward fortifications or near Kennington Cove.

The terrain surrounding Louisbourg harbour was drained by numerous streams which emptied into three sizeable barachois and a smaller inlet described on plans as an "etang". A barachois, according to the Larousse dictionary, is a "small, natural port, shallow, enclosed by rocks at water level". The three on Louisbourg's coast seem to have conformed to this definition during the 18th century since the causeways which exist today were not constructed until the 20th century. Pichon did note, however, that the French tended to use the term "barachois" for any pond near the shore which was separated from the sea by a "grave ou chaussee de cailleux". [56]

The presence of the streams and barachois had the effect of dividing the land around the harbour into five sections. Though it is generally easy to determine which area was meant, the distinctions are sometimes blurred and confusion arises. The sections of the harbourfront were:

In January, 1754, Gratien D'Arrigrand, who had been granted a large concession north of the fond de la baie, described the area in the environs of Lac de l'Avé Maria. To the south of the lake, he said, toward Louisbourg, the land was very poor, covered with "beaten-down fir". It was, he concluded, proper for nothing. The approaches to the lake from Louisbourg were so wide that nothing ventured there except hunters and men wishing to fish for trout, plentiful in this lake, through the ice. To the north, D'Arrigrand continued, "the shores ... are fir, much cut up, with many trees thrown down on one another by gales, and others still standing; this does not make a very gracious country to travel through". However, just a short distance from this area was "magnificent hardwood and excellent lands". [58]

One topographical feature which was noted on most maps is Montaigne Du Diable, located at the border of lieutenant de roi Bourville's habitation north of the fond de la baie. A lake of the same name was situated at the foot of the hill on Bourville's property. It was a name the French seem to have been fond of since they give it to at least two other pieces of high ground, thus making confusion inevitable. The second Montaigne Du Diable is on the road to Mira, northwest of Louisbourg. It is the one referred to by La Roque in his 1752 survey of the island. The third mountain of the same name was situated near the Grand Lac de Mire along the road which led there from Louisbourg. [59]