For many people, visiting a wildlife park is a must-have bucket-list item. Few travel experiences can compare with watching wild animals wandering freely in wildlife reserves, enjoying their natural habitat. Here are some of the very best wildlife parks from all around the world.

1. Masai Mara National Reserve, Kenya

The Masai Marais located in the southwest of Kenya and is one of the most important and well-known wildlife conservation areas in the world. Covering an area of 1,510square kilometers, the Masai Mara National Reserve consists of the grasslands, mountain highlands, lakelands and valley.

Those looking for an unforgettable traditional wildlife park experience should look no further than the Masai Mara National Reserve. Famous for its natural diversity of animals, you can expect to see vast numbers of leopards, elephants and lions. The wildlife park is also home to over 450 bird species.

2. The Serengeti National Park, Tanzania

Listed as a UNESCO World Heritage Site, the Serengeti National Park is a land of beauty that is one of the last naturalistic wonders left on this planet. This wildlife park is the symbol of Africa, and also one of the world’s oldest ecosystems to ever exist. Located in the northern area of Tanzania, the Serengeti National Park has also been famous for the annual migration (迁徙) of wildlife to permanent waterholes.

During this phenomenon, you’ll get to see vast herds of zebras, buffaloes and elephants migrating to the waterholes due to the change of season, followed by predators(捕食者) on the hunt for them.

3. Tierra del Fuego National Park, Argentina

The Tierra del Fuego National Park, located at the southern tip of Argentina, is nestled between the Atlantic and Pacific Oceans, thus featuring a dynamic weather ecosystem with beech forests, mountains, waterfalls and glaciers (冰川). Not quite the image you may have in mind of a wildlife park being muddy, brownish and all dry landscapes.

It is a most breathtaking wildlife park, home to beautiful species such as eagles, rabbits and North American beavers. Aside from basking in the sightings of these wild animals, visitors to Tierra del Fuego often go hiking and fishing there.

Native to forests of Central and South America, glass frogs in the Centrolenidae family get their name from their skin and muscles that help them be perfectly fit to live in their jungle environment. Turn the frogs over, where the effect is the most impressive, and you’ll make out their hearts, livers, and other organs through their hyaline stomachs.

And in a study published in the journal Science, researchers have discovered an amazing mechanism (机制) the animals use to become so clear.

When glass frogs go to sleep, they take in 89 percent of their brightly colored red blood cells into sacs (液囊) in their livers, which reflect incoming light and make the frogs appear nearly unseen. With their red blood cells out of view, the frogs become twice to three times more clear -a trick scientists believe helps the animals avoid being killed and eaten by their natural enemies.

“The trick is really hard to do, because their tissues are full of things that take in and spread light. And transparency (透明) is normal for many creatures in water, but hard on land,” says study co-author Jesse Delia. “Red blood cells also take in a lot of light, and we found that the frogs can actually hide themselves by packing them into the liver.”

Not only are the findings interesting, but the researchers attach great importance to them. That’s because many red blood cells in one place usually form a clot (血块), which can block and lead to a potentially life-threatening condition. But the frogs can seemingly clot and expand their red blood cells at will — without any negative effects. This may mean the animals already have what medical researchers have been seeking for decades: a biological mechanism which prevents too much bleeding while also preventing too much clotting.

There’s no end of dangerous sports to try out in Southern Africa-bungee jumping, skydiving, water rafting. But for a new rush, how about swimming face to face with a killer shark?

The public seems interested in finding danger in this activity. Cape Town’s aquarium has been filled with divers who want to swim with the sharks since it opened its tanks to paying visitors last month. Around 70 tourists aged between 12 and 40 have paid 275 rand (US $55) each to spend up to an hour with Maxine, Dee and Floyd, the aquarium’s three sharks.

And conservationists say the project should help change the damage done to the shark’s image by the popular movie Jaws.

“People will always pay money to be a bit daring,” said Paul Loetter, an aquarium diver. “Most people think every shark is dangerous, but they’ve got the wrong idea.”

Each visitor can swim with the sharks and other fish that share their tank, guarded by aquarium divers armed only with a stick to keep off any over-friendly sharks.

“This is part of a communication and education programme to show sharks are not as bad as everyone makes out,” said Tony McGyre, operations manager at the aquarium.

Len Compagno, head of the South African shark research center, agreed. “It’s no joke to play around with a big dog. In the same way, a three-metre-long shark could put a few holes in you.” he said.