Pushing fun to the extreme

(CNN) -- Jumping off a 1000-foot cell tower to release a parachute at the last possible moment is some people's idea of a good time.

Others like to leap out of a plane in a wingsuit and fly around for as long as possible before opening a parachute and -- hopefully -- floating gently to the ground.

Why are some people excited by these kinds of activities and others horrified?

Though environment plays a role in this type of personality development, it is unclear whether some people are predisposed to these kinds of risky activities because of biology, says Frank Farley, PhD, psychologist at Temple University, who has studied for decades what he calls people with "type T" (thrill-seeking) personalities.

"These people want to lead an exciting, adventurous life," he says.

"These thrill-seekers thrive on the uncertainty associated with activities that most people would consider scary."

CNN.com examined five activities that are not for the faint of heart.

1) Underwater cave diving

The underwater views can be like nothing you've ever seen, according to many cave divers.

"I think it can be very beautiful and like looking at sculptures underwater," says cave diving instructor Jim Wyatt of High Springs, Florida. "But you don't see very much sea life in these caves," he says.

James Cameron brought this adventurous sport to the silver screen, recently, with his film, "Sanctum." Movie-goers watched in horror as cave divers fought for their lives after getting stuck in a cave due to a torrential downpour.

Cave diving requires specialized equipment and training, says Wyatt.

"Among other things, cave divers need different types of suits, masks, lights and gas supplies than a recreational diver since the conditions are much more rugged."

Cave diving is one of the most dangerous kinds of diving or caving in the world and is rarely practiced due to the skills and equipment required, according to experts.

And it's expensive too. The basic gear costs about $9,000, experts say, which does not take into account training, site fees, travel, quick-fix spare parts and other miscellaneous costs.

2) Heli-skiing

If you have a need for speed and dream of exploring uncharted scenic lands, then heli-skiing may be for you.

"Heli-skiing is a pinnacle experience for anyone who loves the sport of skiing or snowboarding," says Mike Sadan, the general manager of a heli-skiing outfitter in Whistler, British Columbia.

In heli-skiing, skiers travel by helicopter to areas not accessible by other means, like a ski-lift.

Sound dangerous? Maybe.

"The procedures are very structured and risk is minimized although we know it's there," says Sadan.

Frank Wells, former president of The Walt Disney Co. died in a helicopter crash during a heli-skiing trip in 1994. But these types of accidents are rare, according to experts.

Heli-skiing is only recommended for advanced skiers, due to the extreme technical and physical demands involved in the sport, say some experts.

Heli-skiers brave the risks in order to ski through untracked powder and breathtaking mountain scenery.

In heli-skiing, skiers don't normally jump from a helicopter to the ground. Instead, the helicopter lands and the skiers hop out for their high-altitude adventure, Sadan says.

Though heli-skiing packages vary, the sport can be pricey, from $800 to $1,000 a day per person, he says.

"Most people that do it have a good income and love skiing."

3) BASE jumping

Imagine jumping off a high cliff, a tall building or even a bridge.

If you're a BASE jumper, then this hair-raising thrill is probably part of your DNA.

Why would you do this? "Because you can," says a jumper named Andy. "It's one of the last true sports where you can really push the envelope."

Andy did not want to reveal his full name for this report, since this sport is illegal in some parts of the country.

BASE is an acronym for Buildings, Antennas, Spans (bridges), and Earth (cliffs): referring to objects that provide a platform for jumpers.

This activity differs from skydiving in that it happens at altitudes of less than 2,000 feet. In contrast, skydivers usually jump from 3,000 to 13,000 feet.

The BASE jumper greatly reduces the margin of error compared to jumping from an airplane, because they are jumping a much shorter distance. Some BASE jumpers say that danger adds to the excitement.

Gear made especially for BASE jumping costs between $2,000 and $3,000. This may be one of the "cheaper" extreme sports, but it is still dangerous.

"I've known a lot of people who have broken their bones in this sport, myself included," says Andy.

4) Wingsuiting (aka wingsuit flying)

If you ever dreamt of soaring through the air like a bird, then wingsuiting may be for you.

"It's quite a rush and the people who do it absolutely love it," says Hans Paulsen, the owner of a skydiving operation in Rockmart, Georgia.

A special jumpsuit, called a wingsuit, allows skydivers and BASE jumpers to soar through the sky with their arms spread open. The suits average about $1,000, says Paulsen.

"Many skydivers say that when in a wingsuit, it's the closest thing to flying that we can experience in free fall," says Tony Sciarini, a wingsuit flyer.

Paulsen says a normal skydiver falls about 120 mph during free-fall. In a wingsuit, you can slow this down to about 40 mph, resulting in a free fall that's three times longer.

A wingsuit flight ends with a parachute opening up, like a skydiving experience.

An important note: This sport is not for beginners. The United States Parachute Association requires any jumper flying a wingsuit for the first time to have a minimum of 200 free fall skydives, made within the past 18 months, as well as training by an experienced jumper.

If you use a plane, the price for a wingsuit jump can average about $25 per flight, says Paulsen.

Glenn Singleman and Heather Swan set a world record for jumping from the highest point in wingsuits -- they fell 21,666 feet from a ledge on Mount Meru, Garwhal Himalaya, India, in 2006, according to the Guinness Book of World Records.

5) Mountaineering

The sense of adventure, the challenge of climbing at high altitudes and the spectacular views are what attract many people to mountain climbing.

History and literature is filled with stories of mountaineers -- their successes as well as their failures.

"Everyone has their own reason for mountaineering, but I enjoy it because I get to travel to unique places, meet a lot of interesting people and I like the personal satisfaction of accomplishing a tough goal, " says Tom Jarosz, an experienced climber from Norcross, Georgia. "I also enjoy the training aspect for preparing for an expedition and how it gets me into shape."

Training for a trip up a mountain can take weeks, months or even a lifetime depending on the goal.

If you are new to this type of adventure, then choosing the right guide is important, as it can make or break the entire experience.

"When you hire a professional service of any kind, you'll want to look at their safety and success record, credentials, certifications, ask for references and consult friends and acquaintances who have climbed previously," says George Dunn, the co-owner of an outfitting business in Washington state.

Experts, like Dunn, say mountaineering trips require extreme winter clothing that can cost thousands of dollars. Basic tool kits like an ice axe, harness and crampons can cost about $250. Camping equipment and other essentials, like food and supplemental oxygen are often provided in outfitter packages and range significantly in price depending on the type of trip you take. Some of the most expensive expeditions can cost tens of thousands of dollars.

Some extreme mountaineers set goals to climb the world's Seven Summits, which are the highest mountains of each of the seven continents. Mount Everest in Asia is the highest at 29,035 feet.

In 1985, Richard Bass, a U.S. businessman became the first man to climb the seven summits after reaching the top of Mount Everest, according to many historians.