How many layers do the Mayan worlds have in Mayan mythology?

Answer 1

The Maya pictured a universe consisting of heavens above and underworlds below, with the human world sandwiched in between. The heavens consisted of 13 layers stacked above the earth, and the earth rested on the back of a turtle or reptile floating in the ocean. Four brothers called the Bacabs, possibly the sons of Itzamná, supported the heavens. Below the earth lay a realm called Xibalba, an underworld in nine layers. Linking the three realms was a giant tree whose roots reached into the underworld and branches stretched to heaven. The gods and the souls of the dead traveled between worlds along this tree.

Answer 2

Apparently, they believed in 13 levels of an upper world (which we could call heaven), one level of the middle world, and 9 of an underworld.

(See ancient.eu/Maya_Religion/ for more information.)