The Exit Portal is the end goal of all the lemmings in all of the levels. Levels can have multiple exits (up to 4), and sometimes they are hidden behind terrain.
Types of Exit Portals
Exit Portals come in all shapes and sizes spanning across all Lemmings games based on level theme. In a 2 player game, both players' lemmings will go into either player's exit, with the objective being to get more into your own. The Blizzard level Check Your Hints! has false exits that are essentially decorations. Lemmings: The Puzzle Adventure has some variations on the functionality of exit portals. In that game, there are locked exits that require often randomized "?" tiles to be dug, and exits that can only allow a limited number of lemmings. Some later levels and challenge levels split the lemmings into groups marked by colored shapes, which can only go into the matching exit.