Don't let that stop you. I'm a fellow INTP and similarly reserved, but I have come to love traveling alone to places I don't know. For me, the trick is to be open to encounter but not to specifically seek it out. I spend most of my day solo, but deliberately put myself in places where conversation might happen naturally at regular intervals throughout the day. If you're eating, eat at the bar/counter; people are more social there. Drift into a tour group at a museum. If a comment comes to you, make it, and notice who smiles. Encounters will happen.

Resist the urge to pull out reading material. I had a very interesting conversation about ontology with a Swiss mathematics grad student while sitting at a picnic bench in Christchurch, NZ: the conversation started with a seagull and a plate of French fries. Wouldn't have happened if I had my nose in of a book. :)