Tabatinga is the jumping off point for boats along the Amazon, either heading west to Iquitos in Peru of east to Manaus. Its not a particularly attractive place! If you're coming in from Peru, you will go through passport control on the Peru side, but on the Brazilian side you'll need to find the local police station yourself to show your documents (inc. Yellow fever certificate, very important). Boats to Manaus go 3-4 times a week. Book a spot on the mid-deck (your hostel will help you) arrive early to grab a spot to hook up your hammock (my boat was leaving at 2PM, I hooked up my hammock at 11 and went for lunch, no-one will move it). You can buy hammocks in Tabatinga, but I'd recommend buying one elsewhere. On the boat, take lots to read because there is very little to do apart from watch the river, and you don't see much wildlife apart from birds (and the odd river dolphin if you're lucky). Food on the boats on the Brazil side is OK (I've heard its not so good on the Peru side), and if you get board with it, there's usually a bar/cafe on the top deck selling toasties etc. Bring lots of drinking water though.
