_{This is part 46 of the puzzle series Around the World in Many Days. Each part is solvable on its own.}

Dear Puzzling,

Today I have pre-emptively ticked off a destination from my future to-do list. So when this one shows up on my list a few years from now, I’ll have already visited it and can mark it as done immediately. I like thinking ahead! I have visited a pretty remote island full of thick rainforests, pristine waters, caves and hiking trails. I have had the place pretty much to myself as far as tourists are concerned, so I suppose it’s perfect timing for me. Can you guess where I am?

Love, Gladys.

Solve on Penpa+

Across
1. Murder is wrong (3)
5. Ornate sailing vessel has nothing inside (7)
10. Hurt king in monarchy (6)
12. Agents recovered initial records (4)
13. Cooking our tenth sauce base (4)
14. Lying about a vaccination where Cabo is (4)
16. Rangers, in play, getting wins (7)
20. Turn away as prophet eaten grotesquely (8)
23. (???)
27. For example, David Bowie’s “Ziggy Stardust”, in key of G, exhibited real eccentricity originally, looking back (5,3)
32. At last, long-awaited canopy is unfolding (7)
35. One short and pale (4)
36. Slowly flow westward where animals are kept, then east (4)
37. The supreme among leaders, before the start of Revolution (4)
38. Something to get you going (e.g. nine bananas) (6)
39. Senior is accomplished; acquires money (7)
40. Child of literature and language enthusiasts educates principals (3)

Down
1. Native American is no wise man (5)
2. Robespierre’s brother to liberate captured revolutionary chief (5)
3. Normandy town’s elected leader is in prison (4)
4. Piece of Jimi Hendrix’s axe (4)
6. A thought that’s comical (7)
7. King does damage in the studio (3)
8. Hungary’s PM’s striking down article describing Mars and Venus? (4)
9. Film in which old man transports his house near a mountaintop and black stream (5)
11. Instrument with many mechanical parts (and no AI) buckled under pressure (5)
15. Former sea god seen in a lake (4)
17. Balkaner’s ready for Uncle Vanya part (3)
18. Richard from Chicago deprived of right? Oh dear! (3)
19. Maturity – it makes man succeed (3)
21. Give up running, wild one! (3,4)
22. Action perhaps performed by Jack Frost up in 11 down (3)
23. Feature of San Francisco Times describing area (3)
24. Place where Brigham Young brought his followers is a little bit out ahead (4)
25. It protects couples for a queen and king? (3)
26. Russian frontman of the French band in which Trent Reznor plays (5)
28. Rope referenced in Glass Onion? (5)
29. Roman poet’s half-hearted observance (5)
30. Concur with American environmentalist, but not entirely (5)
31. Ancient instrument fabulist recounted (4)
33. Advanced upcoming novel, first in trilogy (4)
34. Hard liquor knocked back not far away (4)
36. UK PM no longer in possession of British keep (3)

Gladys will return in Breathe, breathe in the air.