Launched in 2017 by German shipyard Nobiskrug the 144 meter Sailing Yacht “A” is the largest sail-assisted motor yacht in the world; while incredibly unique in many ways, the 8 deck vessel’s most interesting feature may be its underwater observation pod at the keel fitted with 12 inch thick glass.

https://www.reddit.com/r/WeirdWatercraft/comments/1sjznqv/launched_in_2017_by_german_shipyard_nobiskrug_the/

Just a weeeee bit extravagant.