In 1992, IEASM began mapping the area around the port of Alexandria and in 1996 they extended their research to include Aboukir Bay, tasked by the Egyptian government to discover Canopus, Thonis and Heracleion, all believed to have been reclaimed by the Mediterranean Sea. This research allowed them to understand the topography and circumstances that caused submersion of the area over time. The team used information from historical texts to establish the areas of primary interest. The survey of Aboukir Bay covered a research area of 11 by 15 kilometers (6.8 x 9.3 miles). Beginning in 1996, the mapping of the Aboukir Bay took years. In 1999 they discovered Canopus, and in 2000 they discovered Heracleion. The site of the sunken city of Heracleion remained hidden in the Bay of Aboukir for so long because the remains of the ancient city are covered with sediment. The upper layer of the sea floor is made up of sand and silt deposited as it exits the River Nile . The team from IEASM was able to locate remains by creating detailed magnetic maps, which provided the evidence needed to finally pinpoint the location of Heracleion.