ATLANTIS
The island of Atlantis is said to have been made when the God of the Sea, Poseidon, fell in love with a maiden named Cleito. He used his Godly powers to surround the hill in which she dwelt with vast ocean, thus dissallowing any man from taking her.
The kingdom that would grow on this island consisted of concentric rings of land and water ways. Only Royalty, Servants and Royalmen were allowed into the City of Atlantis.
There have been writings recovered from many civilizations around the world that have mentioned a scientificly advanced island city. To the Egyptians, Aztecs, and Mayans, they were peaceful and shared technologies and culture. This explains why two different structures (the Pyramid and Temple) were so simular yet half-a-world away. To the Romans and Greeks, who actually refered to them as Atlantis, they were extremely violent conquerers who constantly showed off their wealth and power.
The only records describing the demise of Atlantis were in Platos two works "Critias" and "Timaeus" written in the 300's BC. According to the Greek Philosopher, a brilliant civilization once existed on Atlantis. During one day and night, great explosions shook the island, and it sank into the sea.
KRACKEN
The Kracken was a giant beast of the ocean which was unleashed by Poseidon in the classic myth "Clash of the Titans" and eventually would destroy Hercules and Madussa. The word Kracken means octopus, but the picture provided by reader imaginations was, and still is, much different.
MERFOLK
Early ocean explorers and seamen reported sea creatures with the upper-half of a human, and the lower half of a fish. It is believed by modern historians and scientists that the manitee, also known as the sea-cow, was what the seamen were seeing.
In Greek mythology the female of the species, the mermaid (or siren), would lure them to destruction with her irrisistable singing. In European mythology, they are peaceful people and are said to have magical and prophetic powers. Though their life-span is far longer then the average human, they are mortal and have no souls.
Much like Expansionist Civilizations have Scouts, Atlantis has Merfolk: the sea-scout. This brings the exploration of other continents that Atlantis is famous for.