Not quite an arch to nowhere, as there is an informal path through the coastal scrub to the cliff for a great ocean view. The path can be followed south to the statue park if you feel like walking. This is also pretty much the highest part of the island, but not quite high enough to give a clear view to Cancun. The ocean is usually quite empty of traffic, with occasional trawlers and naval vessels on exercises passing by. There are not a lot of local fishermen coming out this way, but at night it is a major highway for cruise ships sailing north. There are often large flocks of frigate birds circling above and rising on the thermals, and we were recently lucky enough to see an eagle soaring above, which is quite rare on the island.
The cache is not too difficult to find, please bring your own pen, and even here where it is fairly quiet you need to be aware of muggles.
CONGRATULATIONS Pippitt and pitbul99 FOR FTF 
BYOP