The Forest of Peldain

"Set on the water world of the Hundred Islands, the Arelian empire attempts to seize control of the last island, Peldain, which within its dense forests contains an independent kingdom and an ancient secret." (cited from the novel's Wikipedia entry) From the back cover of the DAW first edition: "The Forest of Peldain - Life was not possible on that watery world except on the Hundred Islands. The Empire of Arelia ruled them all - all except for one. Peldain was entirely covered with a forest so impenetrable and so deadly that all attempts to explore it were disastrous. Then a man came out of that jungle - a human - who told the Arelians that at the center of the island a secret kingdom flourished. There was nothing for it but to organize an expedition. However deadly the alien forest might be, if one man could get out, an army could get in. So Lord Vorduthe landed and began an assault on the great green enemy. Nobody would have foreseen the horrors with which the forest defended itself. Nobody could have foreseen the price that would be paid by Vorduthe's men. And only Vorduthe himself could learn the incredible secret of the island... if his mind could stand it!"