Sure! For the uninitiated, Tenochitlan, the Mexica capital, was built on an island in Lake Texcoco. The greatest difficulty the Spanish and Tlaxcalans had the first go round (after murdering Motecuhzoma and trying to flee with stolen loot) was that the causeways linking the city to the shore were pretty good killzones from war canoes.
After la noche triste and a year’s recuperation, Cortéz actually sent back to Veracruz for some of the ships he scuttled when his force first arrived (better conquer shit now, there’s no going home). on the shores of Texcoco he ended up rebuilding 13 ships (after realizing it was p. dumb to rebuilt them in Tlaxacallan), infamously waterproofed with tallow from corpses (but who knows really). To the best of my knowledge, the main benefit they afforded was being able to drop troops (in particular mounted ones) at portions of the city not accessible by causeways and get food around. Tactically, they were too large and slow to be much direct use except as big dumb gunboats for covering causeway-moving troops, and the Tlaxcalans and Texcocans used canoes to do most of the blockading and raiding. The Mexica eventually started putting sharpened stakes in pits throughout the lake to catch the lower-drafting barques, and it was a p. minecraftesque built and destroy-a-thon to control their movement. It’s important to note that the second battle of Tenochtitlan was a siege, and the single most decisive blow was probably Alvarez and Olid wrecking the city’s main aqueduct (Lake Texcoco has salty and sweet water zones, and Cortes wrecked the dams keeping the two separate).
Dysentery and starvation were the main weapons of the second battle, and it’s really hard to estimate how much the spanish actually did themselves – there were somewhere in the realm of 1,500 Iberians and maybe as many as 200,000 indigenes maintaining the siege, and as it went on more Aztec tributaries defected and further isolated the capital. Even after small pox, it took 6-7 months before the Mexica surrendered.