From the Publisher's website:-
WATER REALM is the second official expansion for the fantasy board game PROPHECY. Like the first expansion, DRAGON REALM, it brings new cards, a new game board, and several exciting variants to the game. It can be used with or without the DRAGON REALM expansion, but you will need a PROPHECY base game in order to play.
Dig for buried treasure on an island in the middle of the ocean, pass through the Gate to the Water Realm to explore an undersea world of magic and monsters, and be the first to defeat the Lord of the Sea or the Ancient Squid and earn the ultimate prize — a fabled Pearl of the Abyss !
Please note that the cards in WATER REALM are not fully compatible with the cards from DRAGON REALM or the original printing of PROPHECY. We no longer do business with the original printer, nor even know if they are still in business. Thus, trying to print the cards exactly the same would lead to many alignment issues. For this reason, the cards differ slightly (mostly the card backs). If you wish to fully enjoy your copy of WATER REALM, we suggest that you sleeve your cards.
NB you must own Prophecy to be able to play this game