Toto Lake is a location found in Breath of the Wild.
Breath of the Wild
Toto Lake is a body of water found just north of Zora's Domain. Water from the lake flows northward, down the waterfall, spilling out into South Lake Akkala. The Lake itself is filled with ruins of an old building. A treasure chest can be found within the ruins which contains the Zora Helm, one of the armor pieces that are part of the Zora Set.
When the water flows down from the Toto Lake, down the waterfall, Link can paraglide behind the waterfall. On a ledge near the top, there is a treasure chest hiding behind the waterfall that contains a Ruby gem. East of the Totok Lake, there is another, very similar sized waterfall. A chest is also hidden behind this waterfall, with this one containing a Silverscale Spear.
Just east of Toto Lake, on the higher ledge, there are some fairy lights moving around. If Link catches them, he will find a Korok.
Nearby Korok Seeds
Catch the fairy lights.