The Boat on the Roof is exactly what the name says: a wooden fishing boat resting on a house in the Lampulo neighbourhood. Compared with PLTD Apung 1 it is small, domestic, and therefore more intimate. You stand in a lane, look up, and understand that the sea arrived here with enough force to rearrange the city.
The site is modest and usually quick to visit, but it deserves respect. It sits in a living neighbourhood, not a theme park. Combine it with the Tsunami Museum and PLTD Apung 1 rather than treating it as a photo stop in isolation.