tonight on a special edition of "nightline," unicorns of the sea, we ventured deep into the arctic circle in search of the serious narwhal, one of the world's most elusive and dangerous creatures. close call as a planet literally splits over before our eyes. our team faces a desperate scramble to make it off the ice. arctic adventure. it's an epic journey to the edge of the world. whoo! >> announcer: from the global resources of abc news, with terry moran, cynthia mcfadden and bill weir in new york city, this is "nightline," august 21st, 2012. good evening, i'm terry moran. tonight, a great adventure.

we take you to the edge of the world. a journey of a lifetime on a quest in search of an elusive creature known as the unicorn of the sea. it's a nar wall. an arctic la viason. what we discovered it a vast and sometimes deadly. linsey davis and our producer alex waterfield, journey to the far north, just getting there was an adventure of its own. >> reporter: it's in the middle of the night, in the middle of nowhere in one of the most inhospitable places in the world. aside from my guys, i'm all alone. the wind is punishing. the only thing my iphone is good for is taking video. >> this location is so remote, we've had to take three planes. and now we're into our third hour of getting pulled by a

snowmobile. >> i can't see much on the phone. my three guides are nice but they're not exactly inspiring confidence right now. what happened? >> yeah, well, it's broken. >> reporter: we're now down to one snowmobile. we just left it back out on the ice, and if that wasn't bad enough -- are we lost? >> we are. >> reporter: i think he's jobing, but this does not bode well. we're deep inside the arctic circle on baffin island. it's bigger than california but with only 11,000 inhabitants, it's not the kind of place you can stop to ask for directions. but this is the price of admission for one of the most elusive creatures on the planet, the narwhal, with that single tusk that can be up to ten feet long. it's the stuff of fantasy, and i for one need to see it to believe it. sooner rather than later.

the narwhal is said to be one of the most vulnerable species vulnerable to climate change. and all around us like these big cracks in the ice, cracks that shouldn't be this wide this early in the summer. my mom would not be happy about this. the arctic sea ice is literally disappearing beneath our feet. on track to be faster this year than any other on record. the effects of the rising temperatures up here are dramatic. just a few hundred miles away from us, these tourists had a narrow escape when an ice wave caused by a falling glacier almost capsized their boat. despite all the obstacles and dangers this far north, we press on. and suddenly, i notice some orange domes on the horizon. it's our campsite. we made it. welcome to the edge of the world, right? >> right. so this is our arctic base camp. >> reporter: i'm greeted with

tom lennartz, our team leader for arctic polar expeditions. >> everything you see here has been brought here. >> reporter: the only tour operator that offers land-based trips this far north. lesson number one for new arrivals, know what's beneath your feet. >> we're sitting on about 4,000 feet of sea ice. it appears it's firm, but it's actually going up and down with the tides as well. >> reporter: how do you know that it's safe? i can be jumping around and i'm not going to wind up in a thousand feet of water? >> no, no, you won't. >> reporter: right there, that dark there, that's the ocean? >> that's the ocean. >> reporter: that's all that's separating us right now? >> that's it. don't think about it. >> reporter: finally, we head to the edge where the sea ice meets the open water, one of the most original and diverse places on the planet. >> 20 people are here right now watching this so i feel privileged every time i come here. >> reporter: as the ice continues to disappear, so, too,

will this fragile ecosystem taking the narwhal with it. >> and it's cold. definitely got to, but we've got the rain coming down and the sleet. but we're going to see some narwhals and that makes everything okay. >> reporter: eric coombs is a budding photographer, and he's on a mission. >> if we can get the narwhals shooting up the big ivory tusks, that's the pinnacle moment. >> reporter: before you see them, you can often hear them, which is why these headphones attached to a nifty underwater microphone come in handy. th contact coughny of sound here is all that is there now. when we come back a close

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so we rejoin linsey and the team for a very close encounter with the mysterious narwhal and then the mortal threat they face on the arctic ice. once again, linsey davis. >> reporter: through the fog which seems to make this moment all the more mystical -- >> he's just behind that patch of ice over there. >> reporter: -- they spot it, an

arched back in the distance. quite a sight for sore eyes. >> i can't believe it we're actually seeing a narwhal. they exist. >> there's actually one right there. >> reporter: and then another one, this one much closer to the edge. before we know it, narwhals are everywhere. >> six or seven of them. >> reporter: but we have hoping for a slightly closer encounter, so we venture out with our fearless leader into narwhal territory. >> so you are kayaking in the arctic. >> reporter: i am kayaking in the arctic. >> this area is the only place in the world to see these narwhals. there, did you hear that? >> reporter: suddenly, we hear something very close take a massive gasp for air. >> do you hear that? >> reporter: as if on cue, the fog clears just long enough for us to realize we're surrounded. >> they're all around us now. >> reporter: and for just a

second, we spot it. don't blink or you'll miss it, that ivory tusk. >> that's very cool. >> that's awesome. what got we hooked on the arctic, they've chosen to come to you. >> reporter: and you're not afraid? >> no, they're not going to hurt you. they're just curious, they're just wondering, "what are you doing hery this is my backyard." >> reporter: but just as quickly as the narwhals appear, they're gone. a reminder just how vulnerable these creatures are to climate change. but rising temperatures around just affecting the narwhal. there are 4 million people living here in the arctic, as our guide showed me, this is not a winter safari destination. it's his home. the sea ice is his highway. his livelihood, that's how he feeds his family. >> i love hunting were my grandfather. >> reporter: so that's one of your favorite things? >> yeah. >> reporter: hunting for seals.

>> yeah. >> reporter: we see for ourselves that hunting for seals isn't easy. and with temperatures rising it's getting harder, the ice is too slick most of the year to use a traditional dog team. the iron dog he uses isn't exactly stealthy. the seals can hear him coming from miles away and escape in the ocean below. i think he's very cute. that is, when they can escape. we're on our way back from a day of narwhal spotting when we happen upon his seal pup. we thought it was just a photo op. we couldn't be more wrong. i word of warning, what you're about to see is graphic. is it sad at all. >> no. >> reporter: it seems so cute, it was just a little baby. >> it's just an animal. the creator gave us this to survive on it. >> reporter: but how do you explain this to westerners who

say this i cruelty to anals. >> this isot cruelty, this is our food. this is how we did it for thousands of years. >> reporter: a way of life, like the ice itself that is slowly disappearing. weather and ice patterns are becoming more unpredictable, as we're about to find out in a frightening way first hand. >> big crack behind charlie. >> reporter: back at camp, just a few hours later, a crisis. suddenly, we find ourselves at the mercy of the rapidly melting ice. >> there's a big crack opening up between us. it's melted faster than it should have. so the elders have said we should pack up and go. >> reporter: a crack in the ice is growing with every minute. if it gets any wider it could be impassible leaving our crew stranded on the sea ice. tom, our team leader, is playing it cool. >> what? you don't want to have these guys around? i've got complete confidence.

we'll get it done. i'm not worried yet. not yet. >> reporter: but wildlife photographer eric puts the situation in starker terms. >> we're to have to leave immediately and hopefully, we'll get back to pond before we float out into the ocean. >> reporter: it's all hands on deck to break down camp as quickly as possible. a bit of trend dags at this point as we approach this crack, which they're calling it a crack, i really hope it's that and not a catch. chasm. the race is on and what i see is onliy ominous. it's massive ice and now it's like little islands of ice. we press on, not even smoking snowmobile is good enough to stop until we arrive at the so-called crack which looks a

lot more like a lake. and that blue water open ocean, a thousand feet deep. >> this all happened in less than six days. so basically 25 times the size that it was a week ago. ♪ >> reporter: suddenly, the sound of roaring engines our inuit guide attempts to cross the 80-foot crack to try to get us home. all multivitamins give me the basics.

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íú so i'm at my best. so the race against the melting ice in the arctic continues and intrepid adventurists prepare to make the desperate dash for safety. once again, linsey davis. >> reporter: the snowmobiles make it across the crack.

is it intended to go over water like that? >> it's not intended to, but people do it. with enough speed. >> reporter: we see for ourselves what can happen if you don't have enough speed. >> holy -- >> reporter: a very close call. but what about the rest of us? and the sled. the guys examine a large chunk of ice floating in the middle of the crack to see if it will work as a bridge, team leader tom is still playing it cool, but even he admits it's an audacious plan. >> i've done big cracks before, but the ice is in their backyard, they know what they're doing. >> reporter: so not a doubt in your mind, everybody can make it across. i appreciate that. the laughter quickly dissipates. this is the moment of truth. as the natives test the limits of these sleds and their ability to make it across. the first sled does not fare

well. it careens across the crack like a runaway train. no one's acting very concerned, though i'm thinking this is pretty dangerous. just as i start to think about the worst case scenario, it's my turn. you think we're going to be fine. >> yeah, should be fine. >> reporter: should be fine? should be? okay. all right. if you say so. all right. we made it. thank you. the entire team is soon distant in the arctic as it makes its way across with varying degrees of success. >> you okay? >> reporter: but success, nonetheless. >> that's everyone. we're across the crack.

>> reporter: tragedy averted, at least in the short run. but the long-term outlook is rather bleak. take a look at how much ice there was in the arctic during the summer just a few decades back. now, fast forward to what's left today. scientists say at the current rate, summer sea ice in the arctic will almost certainly be gone in the next 10 to 20 years. we saw first hand the melting of the ice is cause for real concern. in fact, there was only one occasion where we actually saw the benefit of a crack in the ice. >> she did a "rocky" da da da da! >> reporter: that was to fulfill a longtime tradition that i just had to try before going home. taking the polar bear plunge. this is the stupidest thing i've ever done. and trust me, membership is not for the faint of heart. >> whoo!

>> reporter: it was fun. i want to do it again. as we make our way back to solid land, the fog that's been dogging us all week starts to lift, unveiling a bright blue arctic sky. and though i was too exhausted to enjoy it, i'm told the view was breathtaking. for "nightline," i'm linsey davis on baffin island. >> what an incredible journey that was. our thanks to the very game linsey davis. and her equally game producer alex waterfield. well done, team. thank you for watching abcnews.com. we hope you check in for "good morning america." they're working while you're sleeping. we're always online at abcnews.com. jimmy kimmel is next. we'll see you here tomorrow.