If you take the Circuito Inferior path through the Argentinian side of Iguazu Falls, you'll reach the entry point for the boat tours. Once inside the boat tour area, there's still a few minutes walk to get to the actual departure area, but along the way are some great spots such as this one to view and photograph the falls, unobstructed.
The boat tours take you literally right up to the falls so you can experience them in all their glory. It's a relatively short boat ride, but totally worth it. You'll want to book the boat tour in advance - ideally the day before to guarantee you get a time slot that works for your schedule. I booked mine through the hotel I stayed at which made things super easy.
View of some of the many falls that comprise Iguazu Falls, a UNESCO World Heritage Site.