Tad Sae is the less dependable but often more relaxed waterfall trip from Luang Prabang. Instead of one big drop, the water spills over limestone shelves into a chain of pale blue-green pools, with swimming spots and forest around the edges. When it is flowing well, it feels softer and more playful than Kuang Si.
Timing matters. Late rainy season and the months just after it are the best bet; in the dry season the falls can shrink enough to disappoint. The usual trip involves road transport and a short boat ride, so check recent conditions before going and do not treat it as an all-weather substitute for Kuang Si.