Ukko is an ancient Finnish sky-god, from whose name is derived "ukkonen", thunder. In the Kalevala he is also called Ukko Yli-Jumala (Ukko High-god). "Ukko" in contemporary Finnish means "old man".
... include the Amazon, the largest river in the world by volume, the Parana[?] with its impressive Iguaçu[?] falls, the Rio Negro, São Francisco[?], Xingu, Madeira and the ...