Here's another passage confirming Leviathan's existence:
24 How many are your works, O LORD !
In wisdom you made them all;
the earth is full of your creatures.
25 There is the sea, vast and spacious,
teeming with creatures beyond number-
living things both large and small.
26 There the ships go to and fro,
and the leviathan, which you formed to frolic there.
The destruction of Leviathan:
1 In that day,
the LORD will punish with his sword,
his fierce, great and powerful sword,
Leviathan the gliding serpent,
Leviathan the coiling serpent;
he will slay the monster of the sea.
Leviathan is already dead:
13 It was you who split open the sea by your power;
you broke the heads of the monster in the waters.
14 It was you who crushed the heads of Leviathan
and gave him as food to the creatures of the desert.
Here is the site for the order of Leviathan,
an Egyptian order dedicated to discovering Leviathan
I'll look more into Latin American beliefs (Toltec, Olmec, Inca, Aztec, Mayan, etc...) today and be back later today or tommorow.