Basic geography could go a long ways, if people believe you. At this point people were exploring the world trying to find the spice Islands, but didn’t know WTF they were doing. Magellan navigating the strait that would be named after him was impressive at its time, but now we know the best way from Europe to Asia (and spices and stuff) by sea without any modern canals is by going around Africa. Like, it still sucks and it’s a long trip but it’s doable compared to going to damn near Antarctica.

This assumes I don’t die, can communicate, and am not in the then-unpopulated (and quite landlocked) current location of Denver, Colorado.

Edit: bonus fact: if a sailor managed to smuggle a knapsack full of cloves back, it was worth about as much a house