We went to OMSI last week with friends. Of course we spent time in the usual little-kid hangouts, but we also explored the upstairs exhibits (on bodies, natural phenomena, sewers, and all kinds of other things) and the special exhibit on the Titanic.
The Titanic exhibit was pretty depressing from an adult point of view, but four-year-old Russell & Mia were quite fascinated. I think ocean-crossing cruise ships and lifeboats and icebergs and submarines and wrecks at the bottom of the ocean being covered with bacteria poop (as the guide told them) were all new to them, so although the scary parts bugged them a little, they were too interested to mind as much as I might have been afraid they would.
After we'd seen the exhibit, Russell saw a picture of the Titanic and explained solemnly to me, "That's a picture of the boat that got wet."
I've been trying ever since to think of similar descriptions of disasters. San Francisco: the city that got sort of warm in 1906 and has wiggled a little from time to time. Mt St Helens: the mountain whose top shifted. Jonestown: where a puddle formed once.