As you can tell from the pointless monkey counter, I personally still haven't seen any monkeys whatsoever, flying, white, or otherwise. What they do have here are bioluminescent bugs. Before I moved out, I found one at the Observatory, crawling through the undergrowth with green glowing "eyes" as bright as LEDs. Then yesterday I found a firefly flying around my kitchen.
However, the flying/crawling varieties of bioluminesence pale into the utmost insignificance compared to the water-dwelling planktonic variety, Pyrodinium bahamense. Monday saw a samll group of us give a send-off to a visiting student by means of a trip to the bioluminescent lagoon of Fajardo. Frankly, I'm amazed that no-one has previously said to me (to paraphrase the great Bill Bryson), "You've never seen the bioluminescent bay !? You must go at once ! Take my car." Because this, like the Grand Canyon, is something to do before you die.
It started with an hour-long and mostly pointless but obviously mandatory safety talk and kayaking instructions. Then you get in a kayak and start to paddle out to sea. Of course, at this point (9pm) it's entirely dark, so all you have for light are the lights of the small nearby town, which reflect off the sea and clouds, and the navigation lights affixed to each kayak.
So you paddle through the bay, past all the expensive-looking yachts in the harbour, then swing around back toward the coast and enter a wide channel (it's a 4 mile trip, in total, and lasts about 2 hours). On either side there are trees, which is most places overhang so much that the sky above is nigh-on invisible. It's pretty much pitch dark. At this point you start to notice that the water is becoming a little unusual. The wake from the paddles doesn't quite look right. Let some water drain down your arm and you see little sparks trickling down it. It's like something straight out of Star Trek.
This isn't the beginning. Nor is it the introduction or the preface, but probably only the copyright page. Entering the lagoon proper, the concentration of the plankton increases dramatically. Every paddle-stroke unleashes a deep glowing cloud that persists for many seconds. Get some speed up and the v-shaped wave from the kayak becomes a glowing green thread. Throw some water and the surface of the lake erupts into pale green fire.
There are pictures of this on the net. I won't reproduce them here, because they're as far removed from reality as Harry Potter is to Gandalf. In terms of colour, most of them are simply wrong. In terms of brightness, this is probably impossible to properly capture technologically, because the human eye processes light in a very different way to any camera. What it really looks like, in terms of colour and brightness, is the luminous paint used in those stick-on glowing stars.
An unexpected bonus is provided by the abundance of wildlife. Anything disturbing the water activates the plankton, so fish are clearly seen as glowing silouhettes. They look eerily like Goa'uld. In places shrimp are found in shoals by the thousand, so hit your kayak with your paddle and see something like the flash from an underwater nuke, from which stream away many hundreds of glowing shrimp.
Another unexpected bonus is the wind and rain. The wind causes waves, each crest of which glows. Likewise the rain causes thousands of glowing splashes. This is one of those things that isn't like anything except itself, unless you have to hand a really large quantity of luminous paint.
"When the stars threw down their spears,
And water'd heaven with their tears,
Did He smile His work to see ?
Did I just dare quote poerty ?"
Well, yes I did. I've no idea if William Blake every witnessed a bioluminescent lagoon, but I suspect that if he did he would have died of sheer melodrama. So, in a nutshell, get thyself to Puerto Rico at once and visit the lagoon. It's quite good.