Waterfall

Waterfall was a multiplayer map developed for and intended to appear in the now-cancelled Halo Online. In Season 6: Raven, the map was added to the Halo 3 component of Halo: The Master Chief Collection, the first map to be added to the game since the Mythic II Map Pack in 2009.

Universe and lore
On a far-flung world in the Zezar system; Zezar VI, the UNSC has maintained a network of facilities acting as a fallback option for key personnel and assets. In addition to providing shelter from hostile encroachers, the UNSC has taken great interest in what might lie beneath the planet’s icy surface, as well as peculiar findings on its two prominent moons.

The base seen in the map, is quite active with AV-14 Hornets, D77H-TCI Pelicans, and GA-TL1 Longswords landing at or flying by the base.

Forge
In Forge, three vehicles can be spawned: the Mongoose, the Ghost, and the Wrecked Warthog. The Mongoose uniquely spawns with the Arctic skin by default, the one previously seen on Avalanche.

Production notes
Waterfall is one of several levels intended for inclusion in Halo Online, prior to the game's cancellation. Prior to 2021, little was known about the map as it was never featured in any of the Halo Online testing releases; the only information relating to the map was the text strings in the MS30 Halo Online build referencing the map's name and description. Some concept art was posted online by Pavel Belov showcasing the map's described setting of a hidden UNSC base.

In February 2021, it was announced that the Season 6 Flight build for The Master Chief Collection would contain the map Waterfall for the game's Halo 3 component; following the release of several armor permutations cut from Halo Online in the prior season. This marks the first time Halo 3 has been updated with new developer-made (non-Forge) maps since the release of the Mythic Map Packs in 2009 and the first Halo Online map to see renewed life outside of the original game.