"New Zealand" is a misleading answer, if items only on Tokelau are the answer. This website lists nations in the Countries of the World quiz which are not UN members, and it also lists other ones which have at least UN observer states which are missing from that quiz.
Sigh. One of those quizzes where I tried three Central American countries and all were wrong so I moved on. Only discover the two I didn't try were both correct answers. Frustrating.
Skill issue tbh, both are part of the Mesoamerican Reef System, which is the second-largest reef system in the world and the largest in the Atlantic. Don't get frustrated for not getting lucky with random guesses.
I think the time is pretty good...There's almost enough time to guess every coastal country. I got the ones i was sure of and then just spent about 2 minutes going around the perimeter of each continent. Ended up only missing 2.
Fun Fact: The word 'Atoll' is a loanword that comes from the Maldivian language 'Dhivehi' (it is the only word I know of that comes from Dhivehi). Helped in getting that answer right
https://en.wikipedia.org/wiki/Sabalana_Islands
(In general, I don't think the Category pages in Wikipedia should be considered to be exhaustive.)
https://whc.unesco.org/en/list/262/