The extreme south and north of the North Island could hardly, by any stretch of imagination, be called rich and fertile.  But the island demonstrates the “falsehood of extremes,” for between them is found some of the finest and pleasantest land in the southern hemisphere.  Nearly all of this, however, lies within fifty miles of one or other coast.  When you have left these tracts, and have risen a thousand feet or so, you come to a volcanic plateau, clad for the most part in dark green and rusty bracken or tussocks of faded yellow.  Right in the centre rise the great volcanoes, Ruapehu, Tongariro and Tarawera, majestic in their outlines, fascinating because of the restless fires within and the outbreaks which have been and will again take place.  Scattered about this plateau are lakes of every shape and size, from Taupo—­called Te Moana (the sea) by the Maoris—­to the tiniest lakelets and ponds.  Here are found pools and springs of every degree of heat.  Some are boiling cauldrons into which the unwary fall now and again to meet a death terrible, yet—­if the dying words of some of them may be believed—­not always agonizing, so completely does the shock of contact with the boiling water kill the nervous system.  Many pools are the colour of black broth.  Foul with mud and sulphur, they seethe and splutter in their dark pits, sending up clouds of steam and sulphurous fumes.  Others are of the clearest green or deepest, purest blue, through which thousands of silver bubbles shoot up to the surface, flash, and vanish.  But the main use of the hot springs is found in their combination of certain chemical properties,—­sulphur-acid, sulphur-alkaline.  Nowhere in the world, probably, are found healing waters at once so powerful and so various in their uses.  Generations ago the Maori tribes knew something of their effects.  Now invalids come from far and near in hundreds and thousands, and when the distractions and appliances of the sanitary stations equal those of the European spas they will come in tens of thousands, for the plateau is not only a health-resort but a wonderland.  Its geysers rank with those of Iceland and the Yellowstone.  Seen in the clear sunny air, these columns of water and white foam, mounting, swaying, blown by the wind into silver spray, and with attendant rainbows glittering in the light, are sights which silence even the chattering tourist for a while.  Solfataras, mud volcanoes and fumaroles are counted in hundreds in the volcanic zone.  If there were not such curiosities, still the beauty of the mountains, lakes, streams and patches of forest would, with the bright invigorating air, make the holiday-maker seek them in numbers.  Through the middle of this curious region runs the Waikato, the longest and on the whole most tranquil and useful of that excitable race the rivers of New Zealand.  Even the Waikato has its adventures.  In one spot it is suddenly compressed to a sixth of its breadth, and, boiling between walls of rock, leaps in one mass of blue water and white foam into a deep, tree-fringed pool below.  This is the Huka Waterfall.  It is but one of the many striking falls to be met with in the Islands.