The third and final Photo Rally stamp book in is located in Madlantis, the pirate haven where the majority of its mini-games take place.
Although Majima can't even access it initially (you'll have to increase your pirate level and upgrade your ship before you're allowed in), it quickly becomes a pivotal setting, appearing in several main story missions, including the ending of .
For this particular mini-game, though, you won't be engaging in any of that: instead, your focus is on taking pictures of certain locations.
Madlantis has the second-shortest Photo Rally stamp book, surpassing Rich Island's Photo Rally with just 15 locations (which is nothing compared to Honolulu's 75 Photo Rally spots).
However, some spots are difficult to find, especially given the barebones clues the Alo-Happy team provides.