Situated 170m above sea level at the end of the Mediterranean steps path, the cave was named after a gunner of the Royal Artillery in 1821. According to an 1829 account, the soldier had been "wandering about the summit of the Rock somewhat inebriated" and was absent from that evening's muster. He was feared to have fallen over the precipice and to have been dashed to pieces on the rocks below. Three days after disappearing, however, he reappeared with torn and dirty clothes and a haggard appearance. He had indeed fallen but had landed on a narrow ledge in front of the entrance to the cave, before being rescued.
The Royal Engineers made, Martin's Path, a small approach path above the precipice to facilitate access. A visitor described the perilous journey to get there a few years after it was discovered:
Speleothem inside Martin's cave:
‘The path which we are obliged to traverse in order to get to it, is one of considerable difficulty and danger. We left our horses in charge of a servant half a mile from the cave, and proceeded along a narrow ledge, formed by art and with much labor, about three feet wide, until we reached the desired spot ... The south end and all the eastern side of Gibraltar is – or rather had been deemed, inaccessible, as it rises perpendicularly from the sea, and presents to the eye no ledges or asperities to encourage one to ascend or descent it, no matter what might be his inducement.’
The ledge below the entrance to the cave, which allegedly saved the soldier’s life, has been undercut by wave action, forming a wave cut platform at what was once at sea level. This feature corresponds to the Gunz glaciation (Palao 1969). Sandy deposits here and to the south of the cave, together with a shell breccia deposit 16m above the cave entrance are further evidence of this.
Martin’s Cave has a large entrance facing the Mediterranean. Access to the cave is gained along a narrow ledge of sandstone and conglomerate. Inside is a large chamber with the floor sloping down westwards. There are several columns and some small stalactites and stalagmites. At the end of the chamber the floor levels off into a muddy pool formed by water percolating through fissures and dripping from the formations above. The roof is quite dry in places, without the classic build-up of calcite deposits. The rest of the cave shows evidence of a time when the climate was much wetter, producing the formations found along the walls of the slope and nearer the entrance, which have now dried up.
In the 1830’s Major Richard Hort refers to a local legend surrounding this cave:
Martin’s Cave! . . . the very head-quarters of spirits – the abode of one of the most powerful, and at the same time revengeful demons that ever influenced the acts of men…
He then describes the cave thus:
‘The entrance to St Martin’s Cave is not at all calculated to attract the attention of the casual observer . . . An immense quantity of rough and shattered particles of the Rock first meets the eye, which, when crossed, the interior of the cave, in all its fairy beauty, stands revealed.
The roof, covered with a most beautiful frothy substance, reflecting from myriads of shining flakes, the lights exposed . . . beam forth stars innumerable. The splendid ceiling is supported by irregular stalactites . . . rising into dazzling pinnacles . . . may well persuade the looker-on that he then gazes on a magic scene . . . and although far from equalling St Michael’s Cave in grandeur and size, it greatly excels all others in the brilliant loveliness of it form…’
William Henry Bartlett writing in 1851 appears to give more substance to this local legend stating that:
‘The story goes, that a boy of Gibraltar, who had conceived a spite against some playfellow, proposed to visit the cave with him and two other boys, observing, as they ascended to the fatal spot, " We are four that go up, but only three will come down! " and, watching his opportunity, precipitated his victim into the abyss.’