The New Zealand Railways Magazine, Volume 6, Issue 2 (June 1, 1931)
Steaming northwards through the group, we pass the mysterious disappearing Falcon Island, an active volcano, which sometimes rears a mass of ashes a few hundred feet above the sea, and at other times has been only just visible above the surface. It must rise from a tremendous depth, for this is the neighbourhood of the “Tongan Deep,” where the soundings are about 23,000 feet.
Vavau, the northernmost extremity of Tonga, reminds one of the approach to Picton, for there are miles of deep sounds, with scores of pretty islands, crowded to their narrow golden beaches with the inevitable cocoanut tree, and giving glimpses of little native settlements at every turn. One of the islands is a volcanic and limestone combination, full of caves, and a trip is always arranged by the Tofua's officers to a particularly spacious and beautiful one, which easily, accommodates a launch and a ship's lifeboat. Immense stalactites, richly coloured descend from the lofty roof, and when struck with an oar they ring like gigantic bells.