<...> Shumshu island <...> Lots of rusty old war remains
The image search for Shumshu looks like one giant "random diorama ideas" gallery.

Rusty tank + whale skeleton in one dio? Would have people guessing. Could either be real world, with the two things unrelated and just by coincidence in the same area. Could be a fantasy setting with people having fought giant monsters. Recently saw a build in a modelling magazine ("Damaged", issue

5? 6?) that had a small excavator in 1/32 with the skeleton of a "giant" (actually 1/6 human skeleton).
EDIT: It was issue 6 of "Damaged Magazine".
Teaser:
SOURCECan recommend "Damaged". Mostly off the beaten path as far as modelling magazines go. Lots of abandoned stuff, figures, dioramas, sci-fi and fantasy, kitbashes, civilian things, steampunk stuff.....