Fountains of Healing (shown with blue liquid on my maps) are a godsend in dungeons, because they will heal any character that drinks from them to full. They can be used repeatedly, so a single Fountain of Healing is basically an infinite regeneration point for the party. You can gain a lot of experience fighting monsters near one of these fountains. If you're doing this on level 04 or deeper, make sure there's also a Fountain of Curing (or you have a character who can cure Poison) because you will run into some Poisonous creatures and these Fountains do nothing for that.