Ultima Underworld II inaccuracies [English | German] are available at Hacki's Ultima Page [English | German].
There seems to be a bug with the automap system where any notes you write beyond a specified limit are lost once you close the map.
Website sections dedicated to Ultima Underworld II can be found:
Peroxide, that was making Ultima 1 - A Legend is Reborn, has developed an Ultima Underworld Viewer for both Ultima Underworld I and II. It can be downloaded from their page, directly from here [ZIP].
Pix's Origin Adventures released an Ultima Underworld 3 Design Document on 1st June 2018. The introductory bullet points can be found here at GameBanshee. Like several other Origin intellectual properties, Ultima Underworld 3 never saw the light of day, and this document provides insight into what could have been.
Sir Cabirus' Ultima Underworld II walkthrough has a list of undocumented spells, and a separate list of runestones.
In his post "Ultima Underworld II: Enchantment!", The CRPG Addict examines most of the spells in the game (up to Level 6), and also criticises the magic system.
The map of Lord British's castle can be found:
Maps of all the levels can be found at:
Crowley's "Guardian's antics as seen in UW2" gives a good description of the places (as well as the story) in Ultima Underworld 2.
Pictures of the box cover can be found at the Underworlds section of the Ultima Web Archive.
See the Ultima Underworld 1 info page for remakes and tools, many of which work for both Ultima Underworld games.
Sir Cabirus' Ultima Underworld II walkthrough has a list of Trainers, including the skill they train you in, and their location.
Crowley's "Guardian's antics as seen in UW2" gives a good description of the story and places in Ultima Underworld 2.
Natreg Dragon pointed out a nice video review of the game by Excalibur Reviews.
Rampant Coyote wrote a "Reminiscing about Ultima Underworld" piece on 3rd June 2011.
Mitch Aigner's Ultima Underworld II walkthrough has lots of useful information and can be found:
Sir Cabirus launched a new Ultima Underworld II walkthrough towards the end of 2015, complete with interactive maps and screenshots.
Kikoskia's Let's Play Ultima Underworld 2: Labyrinth of Worlds is a video playthrough of the game (thanks Vividos for finding this).
The CRPG Addict played through Ultima Underworld 2 between April and June 2022. Here's a list of posts from his playthrough: