I'm sure you guys won't have any problems finding something to do! The country is beautiful just about everywhere, the people are really nice, and you should have lots of fruit and milkshakes. and red snapper.

I can't really comment on osa, I just re read the section in the lonely planet & it sounds gorgeous - but if you've got 5 days (is that with a travel day on either side?), I think most flights come in late at night - and then you're probably going to have to spend the night near san jose or liberia (whichever you travel into) and if you're driving/taking a bus to Osa, that is probably going to take half the day, at least. A flight would probably be better. It gets dark around 5;30 that time of year - so you're going to want to do the get up early thing, and usually you do anyways because you start hearing the traffic and or the chickens crowing. Then on the way back, you're probably going to want to get back to LIberia or san jose the evening before, and get a hotel near the airport.

There's pretty much a zipline place everywhere around the country...

Surfing's usually something that's available maybe every other beach - like $3 an hour to rent a surf board, if there's enough of a tourist industry at the beach to actually have someone there renting one. the more isolated beaches don't necessarily have anyone renting anything.

I was there from the 7th-22nd of November, so probably I was there around the same time... So it was basically the end of the rainy season which is when you're talking about going - I snorkled a bit off the Tortuga islands down across from Curu national park and around playa samara and up around ocotol... Costa rica's really not the best for diving & snorkeling (not that I'd been snorkeling before)... around samara & ocotol, there were sooo much sediment in the water that you really couldn't see much, you could do better in the tide pools. The water was clearer down around the Tortuga islands and I did see a lot of fish - but the coral was for the most part dead. The guide I talked to around the Tortuga's said it's a little better if you go out where people scuba dive, but the reefs still aren't healthy because of people breaking off coral, pollution, whatever. From the books description, it sounds like things are healthier around Bahia Drake in the Osa Peninsula - but it also says the rainy season lasts till Mid December there and to ask how the visibility is in the water.

If you end up maybe deciding to fly into liberia & do the north western section of the country (it's going to be drier in November than most of the rest of the country... however the beaches tend to be dry), this was probably the nicest place I stayed:
http://www.villavistamar.com/cms/fro...t.php?idcat=82
It ran about $65 a night for an apartment with kitchen and just had a breathtaking view, they had a pool & hot tub - and howler monkeys play in the trees around it in the evening:
Pictures of that place in particular are here ('cause i think my photos are better) and you can see in some of the pictures, the sediment in the water.
http://picasaweb.google.com/ImmunoGi...coyaPeninsula#

Their website mentions day trips that are nearby, it is close to volcan Rincon de la Vieja if you want to see some rain forests and volcanos, close to the national park of beaches in the north west corner, and not so far from the beach. American owners. I'm thinking of going back there with some relatives on a relaxed beach vacation as opposed to the 2 week mad dash all around the country that I just did.