Still not satisfied? You can now download an expansion to Ultimate Vault Hunter Mode called "Ultimate Vault Hunter Upgrade Pack Two: Digistruct Peak Challenge." (Note that this is not included in the Game of the Year Edition.)
This Upgrade Pack increases the level cap to 72, and allows players to hit "Overpower Levels" of up to 80. Overpower Levels aren't real levels—you don't get a skill point or stat boosts—but they do make your foes harder, make the loot that spawns stronger, and allow you to equip this higher-level loot. To reach these Overpower Levels, you'll need to complete a series of challenges in a new area known as Digistruct Peak. Each time you emerge triumphant from Digistruct Peak, you'll unlock the ability to play at a higher Overpower Level. Digistruct Peak is the game's hardest challenge to date, and while a full party of four is not mandatory, it's strongly recommended.