Hmm. Water Pokemon aren't my forete, but I'll give it a shot with Otohime and Ryuujin!

(♀) and (♂)

Otohime, start it off with a Mist to fade the field a bit. Then use Waterfall to dash up the waterfall as high as you can go before jumping out Diving down with a silent landing.

Mist~Waterfall (Up the falls)~Dive (to land silently in the water)