Episode 45 of The Trigan Empire
The Great Flood
aka The Sea Creatures
Het rijzende water (Dutch title)
The Rising Water (Dutch title, translated)
Written by Mike Butterworth
Illustrated by Philip Corke
The Great Flood was originally published in 10 instalments in issues 635 (16 March 1974) to 644 (18 May 1974) of Look and Learn magazine.
It is reprinted in Volume 4 of The Rise and Fall of the Trigan Empire (Rebellion).
Plot summary (Dutch)