Diving the B-29 in Lake Mead is no longer allowed (diving last stopped in January 2018), but it had been allowed in the past. In case you’re wondering how a B-29 wound up in Lake Mead, here’s the story: https://www.nps.gov/lake/learn/historic-b-29-bomber.htm. The link includes a YouTube video that can also be seen at https://www.youtube.com/watch?v=tXbwEpTfIkk&feature=youtu.be (it’s a hair over 10 minutes long). You can also read more about the story on Wikipedia.
For those wanting to see a B-29, there are two flying B-29’s, Fifi (link includes a schedule of where Fifi will be touring) and Doc (has an Events tab where you can see Doc’s schedule), and a number of static displays: https://en.wikipedia.org/wiki/List_of_surviving_Boeing_B-29_Superfortresses.
Of the 3,970 built, 26 survive in complete form today, 24 of which reside in the United States, and two of which are airworthy.
Here are the location of known wrecked B-29s: https://en.wikipedia.org/wiki/List_of_surviving_Boeing_B-29_Superfortresses#Known_wrecks (the Lake Mead wreck entry needs updating as dives are no longer allowed to it).
Historic meeting of Fifi and Doc: https://www.ainonline.com/aviation-news/general-aviation/2017-07-26/historic-meeting-b-29s-fifi-and-doc.
Ups Downs Family History 