Borderworld

Borderworld is a two-part shareware adventure, where you play as a modern day archeologist who during the exploration of some underwater ruins, suddenly gets teleported to another world, where he is thrown up on a beach, and has to find his way back by exploring the surroundings, interacting with people he meets which seem to also be trapped humans from other time periods. There is also alien looking ruins, temples and artefacts to search and explore.