For nearly a mile and a half the rock rose sheer from the water's edge, and although the boat was backed into several winding gaps in the reef, in every case the attempt to find a channel proved fruitless. As we approached the spot where the reef joined the island, the rocks became lower, but the depth of water was so little, and the shoal extended so far from the reef, that it would have been impossible to bring the yacht up to the reef, even if a channel existed. "Try the other end of the lagoon, sir," advised the bos'n. "We've let that part alone up to the present." "There's no harm in trying, Mr. Wilkins," replied my father, "though, if I remember rightly, the original coral reef was very irregular at that part, and stretched seawards for a considerable distance." When, after an hour's steady pulling, we arrived at the other end of the reef, we found that the rock was very similar to the rest, being pierced by many deep channels that, as usual, terminated in what the bos'n termed "blind alleys." Three of these were explored without success, but the fourth, some twenty feet in width in its narrowest part, ran in a straight direction for nearly a hundred yards, the walls on either side gradually diminishing in height from twenty-five to less than ten feet. Its end terminated in a mass of broken stone, deposited as if by human agency, in a diagonal direction, affording great facilities for climbing. "It strikes me, sir," remarked Mr. Wilkins, "that the sea is only a few feet beyond the rock. Listen! you can hear the waves bleating against the seaward side." It certainly struck the bos'n, but in a totally different manner from that which he implied, for, without warning, a terrific blast of air, followed by a column of water, was forced through an orifice in the rock, Mr. Wilkins, who was standing upon one of the thwarts in order to make a more complete survey, being in the direct line of fire, received the full force of the discharge, and was knocked completely over the side of the boat, while the rest of us were drenched to the skin. The unfortunate bos'n was quickly hauled on board, little the worse for his ducking, and the gig was backed off beyond the danger zone. "Experience does it!" gasped the bos'n, spitting out a mouthful of water; "which is, I am told, the Latin for 'Experience makes fools wise.' Am I not right, Mr. Reginald?" "Well, what has experience taught you?" asked my father, laughing. "Only what I thought was the case before," replied the bos'n. "And that is, that there's a communication through this rock between the lagoon and the open sea." "I don't see how that can help us," remarked my father. "May be, may be not, sir," observed Mr. Wilkins oracularly. "But if you don't mind, sir, will you land here for a few minutes. We can manage it quite easily by the broken rocks at the side of the blowing-hole."