[lch]

Folket said:
Still, the manual only lists one of the three queens just as it lists only one of every unique summon. The queen listed is the aquatic queen which have less regen then the others. It has only 50%. Could be that it is 70% under water.

The Dom2 info from http://www.freewebs.com/dominions2/spells.html is probably still valid:

Queen of Elemental Water: they will not "heal all their wounds at the end of each round" as expected. The Queen of the Lake regenerates 50%, The Queen of the Sea regenerates 70% and the Queen of the Deeps regenerates 90%.