For GENERAL ideas for things you can do as a DAY trip out of SJ, you really need to check out this classic post of mine from 3 years ago:
http://costaricaticas.com/forums/viewtopic.php?f=1&t=16082&start=16.
I'll cover zip-line tours first and in the most depth since that seems to be mainly what you were asking about. As for "whats the best zipline out of san jose?" I don't think the real question is what is "best". Probably the "BEST" zipline adventures are in tourist areas relatively FAR from SJ (ie not really DAY trips from SJ). The real question for someone wanting to do it as a DAY trip out of SJ is which ones are CLOSEST. IMHO, the problem with any of these zip-line tours is that they're at best really only a HALF day tour with the actual "cable-time" lasting on the order of just a few minutes and the whole tour itself (including platform time and walking to and from the start of the aerial part of the tour) no more than an 1-1.5 hours tops. Because few if any of these tours are really that close to the thickly settled urban area of metropolitan San Jose, for nearly all of these tours most of your time would actually be spent just driving to and from whereever the tour is offered and do you really want to drive for 2-3 hours or more round trip for what amounts to a just a few minutes of excitement?
The most notable exception to that rule is the relatively new zip-line that they've created in
Sabana Park, which is supposed to be nice (6 platforms with 7 zip lines including 1 over the lake) and certainly superconvenient for anyone staying in SJ but which would hardly otherwise be described as the "best". I don't have a weblink for that one but their tel# is 2215-2544.
The canopy tour that I referenced in my comprehensive day trip list was at
Colina del Poas which is in Fraijanes going up towards the Poas Volcano. It is much much more extensive than the one in Sabana Park (and probably much more scenic as well being up so high in the mountains) with 24 platforms and an undisclosed number of cables including the final one measuring 1980ft in length. As something different, they also offer troutfishing if you want to combine your ziplining with another activity as long as you are there (or you can just eat the fresh trout at their restaurant). The potential problem is I don't see where they include transportation from SJ (probably about 1-1.5 hours away) in their rates ($50/pp for the 2hr long zip-line tour) or even offer it for an extra amount. For more info, you can check out their website at
http://www.colinasdelpoas.com/index.php/en/poas-canopy-tour.htmlI also referenced
Turi Bari in that post, though not specifically for its zip-line tour. The direct link to their webpage for that tour is at
http://www.turubari.com/htmleng/?page_id=126. This zip-line tour takes about an hour and includes 16 platforms but only 8 cables, though it also has 2 hanging bridges and one cable measuring an impressive 2135ft. They also have an "add-on" that they call the "
Tarzan Swing" where you swing from a rope (presumably you're fastened to it rather than just hanging on like the ol' swimminghole rope you may have used as a K*D) over a distance of 120 feet (ie must be a really long and high rope).
Another unusual zip-line tour option that they have at Turi Bari is their "
Superman Zip-line Tour". This is only one cable but it is 4000 feet long, and has a maximum height of 315 feet making it (according to them) "not only the longest Zip line tour in Costa Rica but also the fastest since you can reach a top speed of 55 miles per hour". At that speed, the whole thing lasts less than a minute, but what really makes this cable special is HOW you're attached. Rather than wearing a harness attached in front like you are probably used to, on this one they attach you from the BACK so that you're hanging FACE DOWN. You're then supposed to extend your arms and legs fore and aft (as if you were Superman). I haven't done the cable like this at Turi Bari, but I have done that at another zip-line in Honduras and let me tell you, that position takes a surprising amount of upper back strength (thank god it only lasts a minute)
While Turi Bari may not have the sheer number of cables that they have at Colinas del Poas, they probably more than make up for it with sheer variety and much closer proximity to SJ (near Orotina just 45 minutes from SJ using the new highway according to their website, ie half the time it takes to get to Colinas). PLUS they include transportation from SJ in their PACKAGE prices. PLUS they have MANY other things to see and do while there (Aerial Tram, Bamboo, Bromeliad & Orchid Gardens, Butterfly Gardens, Crocodile Breeding Exhibits, Horseback Riding, etc.) so you could easily make it a full-day tour (and need to if you want to get the transportation included). Their rate not including any transportation to/from SJ for INDIVIDUAL tours is $55/ea. Their FULL-DAY tour including transportation (pick-up from the Sleep Inn around 7AM return around 5PM), lunch and aerial tram is $99-119/pp depending on how many adventure tours you want to do.
There is yet another zip-line tour that is relatively close to SJ (45 minutes away according to what I've read) but I haven't heard of anyone who has taken it or know much about it. That is "
Canopy Adventure San José de La Montaña" and is located on the Barva Volcano north of Heredia. I've read that they have 13 platforms, don't know how many cables but that the longest is around 600ft. If you want more info, you can call them at #2266-0782.
There is another zip-line tour at the
Rain Forest Aerial Tram http://www.rainforestrams.com/crpintro.html. As you probably know, they're located about an hour north of SJ on the road to Limon just on the other side of Braulio Carillo NP. Their 1 hour long zip line tour consists of only 7 zip lines and 6 platforms and costs $45/pp a la carte (ie withOUT transportation, though you could conceivably take a public bus to get there). If you go for their full-day Eco-pass, the cost is $104/pp including r/t transportation to/from SJ, lunch and whatever else you want to do there including the Aerial Tram that they're most famous for.
One final zip-line tour I can throw out is located at "San Vicente de Tres Rios, Cartago" (whereever the heck that is though I would THINK it falls somewhere on the SJ side of Cartago near Tres Rios).
Aventuras La Carpintera has 20 platforms and 13 cables (1800m total length). Their tour starts with a 30-40 minute horseback ride. That's all I was able to find out. For more info you can call #2278-3355
Personally speaking of all of these, the zip-line at Turi Baru sounds the most promising particularly since the new highway has drastically cut down the time in getting there.
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As others have said, if you want adventure there are lots of other day trips you can do from SJ that offer you that. Having done PLENTY of both the zip-lines and the
w/w raft trips myself, I can tell you that my personal preference is definitely for the latter. They both often require some time to get out to from SJ, but the actual adventure time on the trip itself is much longer lasting on the rivers. PLUS, if you're gonna be soaked by rain or sweat anyway (as you most likely will be at this time of year) better you should just go for it and get soaked by the river to help you cool off. Thats JMHO, YMMV. Presumably I don't need to offer any links or make any suggestions for rafting as that has already been covered many times on this forum and elsewhere. However, I will throw out a bunch of more unique adventure tour suggestions that you might not have considered.
The first one is
bungee jumping with
Tropical Bungee http://www.bungee.co.cr/. Personally, I haven't worked up the nerve to try this yet either here or anywhere else, though I have jumped out of planes from much greater heights (they have something called a reserve chute, but you don't get any 2nd chances with bungee jumping). If you're up for it, their tour costs $65 for the 1st jump (with discounts for subsequent jumps if you're crazy enough to want to do it more than once

). That price includes r/t transportation from SJ (they charge $10 for transport if you "chicken-out" or are going along just to see your friend kill himself) and they pickup in SJ twice per day at 8AM and 1PM returning 3-3.5 hours later.
Tropical Bungee also offers
rock-climbing if you're into that for $70 for "All Day or until burn-out" (including transport and a snack lunch but requires 4 person minimum). CR is not particularly noted for its rock-climbing and I've never tried it there. However, I did try it when I was in Krabi Thailand, which is considered one of the better places for it (and on various man-made "rock-walls" elsewhere). I can only speak for myself, but can tell you that "burn-out" came quite quickly for me as this "sport" can really do a number on your hands, feet and lower back.
If you prefer an easier descent they also offer a couple of
rappelling packaged (through canyons, one 50m and the other 70m, that may have some small waterfalls but not through the waterfalls themselves). Unfortunately, they don't list any prices for the rappeling though suggest you might get a special rate if you package them with the bungee.
Another GREAT adventure activity that I HAVE done in CR (and elsewhere) is what is known as "
Gravity Assisted Biking". This is biking DOWNHILL (as opposed to the much harder up and down of traditional mountain biking). You don't really need to be in that great a shape to do this. All you need is a reasonable strong hand grip (as you'll be using your brakes A LOT) and nerves of steel as you zip around hairpin turns. I said before that w/w rafting was my favorite adventure activity, but Gravity-assisted biking might have that beat. The big problem is that tours are hard to find because they usually require a minimum number of participants that they don't always get and that, like rafting, it can be expensive when you do find a tour. A few links you might want to check out for more info (such as description of various different tours and prices) are:
http://www.lava-tours.com/day-tours.html and
http://www.costaricaadventures.net/activities/bike-Turr_Volcano.html.
That latter outfit also offers other interesting adventure tours including regular
mountain biking (including uphill),
w/w kayaking (if you have experience) or a
w/w kayaking beginners class ($150/day pickup at 6AM return at 5:30PM) and, the thing I think you might be most interested in, various hiking, rappeling down waterfall and swimming combos (aka
"canyoning"), though they don't list any prices for any of the latter.
http://www.costaricaadventures.net/activities/activities.htmlBTW, some people might consider going
horseback riding to be an "adventure tour". I suppose it could be if you got the horse up to a fast enough gallop or even trot. Usually these tours go at a much more sedate pace. And, IMHO more significantly for us as male mongers, even without getting up to a bouncy crotch slamming pace, going for more than an hour or two of this sport is likely to leave you in a condition where you'll be very sore in the crotch region (and stiff but not in a good way). There USED to be an interesting "Adventure Super Combo Tour" which mixed horseback riding, zip-lining and white water rafting into one long (11hr $125/pp) day tour. I discussed that in this thread
http://costaricaticas.com/forums/viewtopic.php?p=61725. I just went back to their direct link
http://www.costa-rica-tour.net/tours/super_combo.php and it seems they've dropped the horseback part of it (too many sore butts I suppose) and now offer it as "just" a 9hr $102/pp zip-line/rafting tour. So that might also be something you'd want to consider if your time in CR is short, you can't decide between zip-ling or rafting, etc. However, IMHO, any horseback riding "adventure" is probably best left to the chicas and gringas.
Are these enough adventurous SJ area day tour suggestions for you?