Atlantis isn't the only example of a legendary sunken city / island - it was never referred to as a continent - and other possible sites include the South China Sea, Indian Ocean, and Caribbean Sea. Additionally there are the legends of Mu and Lemuria with striking similarities to Atlantis. This is to be expected. Sea levels have risen an average of 120 metres since the last ice age. The rise has by no means been uniform though, some areas have seen a much higher rise than others.
There are many cities now lost to the waves all over the globe, and for a variety of reasons. In China the ancient city of Shi Cheng (Lion City), lies in a valley flooded to construct a dam in 1959. The lake in which it sits is man-made, but that doesn't mean it couldn't happen naturally. A natural dam is more likely to occur in mountainous terrain where landslides are commonplace. Sudden geological upheaval apart, rivers do change their course over time. It's not just small rivers either. The Amazon at one time flowed into the Pacific Ocean, until the continued rise of the Andes blocked its route.
The Nile has changed its course many times and accounts for abandoned ancient cities in Egypt. When the Nile changed its route to the Mediterranean the water supply was lost to cities reliant on the river for irrigation. Conversely, for cities near the coast the threat was not of being left high and dry but sharing a similar fate to Atlantis.
Heracleion is one such city and coincidentally it has ties with our story here. Heracleion, aka Thonis, was on the Mediterranean coast of Egypt near Alexandria. It was said to be where Paris (Alexander) and Helen of Troy took refuge from the jealous Menelaus, just before the Trojan War. Heracles himself was said to have visited the city.
Perhaps a little more significantly, Heracleion is mentioned on the Stele of Naukratis, stating a tenth of taxes from imports passing through Heracleion were to be given to the sanctuary of Neith of Sais. The sanctuary of Neith at Sais being where Solon was told the Atlantis story by the priest Sonchis. Heracleion sank a century after the time of Plato as a result of subsidence caused by an earthquake. Like the Atlantis the priests spoke about, Heracleion probably sank beneath the waves overnight.
With climate change an issue the sea-levels continue to rise. The process is ongoing*. Port Royal, Jamaica, sank after a 7.5 earthquake as recent as 1692. Then there are much older examples like Dwarka, India 7500 BC, and possibly the earliest (though disputed as to whether man-made or natural structure) the Pyramids of Yonaguni-Jima, Japan circa 10000 BC.
*climate change is cyclic according to Earth's orbit and a complete meltdown will paradoxically trigger another ice age. Global warming is hastening the process.
The Aegean is unlike any other area on the planet. It rides atop a micro plate situated in the middle of three other tectonic plates. To the south is a subduction zone where the African Plate dives beneath the Aegean Plate. There are areas in Greece where the results of earthquakes show a split in the land where one side has been elevated up to 12 metres. This opens up other possibilities. For as easily - and dramatically - as the land can be lifted, so too can it fall. It is conceivable the whole floor of the Aegean Plate suddenly dropped at some point.
To summarise we can safely say that large areas and complete cities do sink beneath the waves AND it can happen very quickly indeed AND it is not always a result of sea-levels rising. It is by now safe to assume Atlantis did exist, the next step is to settle the dispute of exactly where this city was situated.