Someone help me here. You mean to tell me that two huge cities lay undiscovered for 1,200 years just below the surface of the water? What do those people do over there?
Apparently not much diving. I'll bet they have been pull up things from there in their nets for centuries.
"To uncover the latest batch of ruins, researchers used geomagnetic mapping, a technique that can differentiate between rock types to detect granite or limestone artifacts beneath layers of sediment. These techniques were instrumental in finding the completely buried ruins of Herakleion, Nur said.
"There was nothing on the surface. Just by diving we would never have discovered this, he said."
I recall a television show on Alexandria..
The question of why it took so long came up..
Seems there are some good reasons..
Weather and tidal forces are the main ones, it seems that the coast off the Nile Delta is a bad place for both..
The Alexandria team went for weeks without being able to dive at all, and when they did, it was only for a few hours..
The weather often kept them out of the water altogether..
When the weather did cooperate, the underwater tides and currents in the dive areas were so strong that the divers were dragged and battered around most of the time, and spent most of their efforts in survival rather than excavtion..
I assume this is the case for these sites as well..
Not only "dirty" water, but strong tides and currents, and generally rough weather through most of the season all contribute to the difficulty of diving..
I would also note that similar problems have been documented in other parts of the mediterranean as well, not just Egypt..
I think part of it has to do with the enormous effect the currents coming through the straits of gibraltor have..
High and low tides cause an incredible rush of water through the straits, which could affect currents for hundreds of miles inside the mediterranean proper..