Why was is so hard for the Aztecs to build Tenochtitlan?

Building Tenochtitlan was challenging for the Aztecs primarily due to its location on an island in the middle of Lake Texcoco, which made access and resource transportation difficult. They had to create a series of chinampas, or floating gardens, to cultivate crops and sustain their population. Additionally, they faced engineering obstacles in constructing causeways and canals to connect the island city to the mainland, all while defending against potential invasions. The combination of these geographical and logistical hurdles made the construction and expansion of Tenochtitlan a formidable task.