Zoos are always a great activity for families, friends and even dates. Zoos also make it possible to see wild animals from areas most people will probably never have a chance to visit. Some zoos even have re-creations of wildlife environments that you can traverse as part of your visit. The best zoos help endangered animals and work to preserve wildlife.

1. San Diego Zoo

This zoo is often named as the best in the nation and is world famous. The 100-acre zoo houses over 3,700 animals, including three giant pandas. The San Diego Zoo also hosts Galapagos tortoises, koalas, meerkats, warthogs, lions, giraffes, polar bears, gorillas, and so much more. The zoo also owns the San Diego Zoo Safari Park, which is about 30 miles away. The safari park is dedicated to conservation and houses animals in habitats the closely mirror their natural environments.

2. Smithsonian's National Zoo

This zoo is free to all and is located in Washington, D.C. The National Zoo first opened 1889 and has grown to include 2,000 animals from 400 species spread across 163 acres. The giant panda exhibit is everyone's favorite attraction, but the zoo also hosts red pandas, otters, elephants, lemurs, orangutans, gorillas, sea lions, meerkats and more. The zoo is located just 20 minutes from the National Mall.

3. Lincoln Park Zoo

This zoo is located in Chicago and was founded in 1868, making it one of the oldest in the country. Admission is completely free. One of the unique aspects of the Lincoln Park Zoo is its $26 million Regenstein Center for African Apes, where you can see gorillas and chimpanzees up close and personal. The nature boardwalk lets you view rare migratory birds while seeing glimpses of the Chicago skyline. The zoo also hosts a 75,000-square-foot African animal exhibit, which hosts its first red river hog.

4. Saint Louis Zoo

The Saint Louis Zoo features a unique sea lion exhibit. You can walk through a 35-foot underwater tunnel and see the 11 sea lions swimming overhead. The zoo features about 20,000 animals from over 650 different species. These include elephants, tigers, alligators, lemurs, snow leopards, penguins, polar bears and kangaroos. Children can enjoy a ferris wheel and a small train that provides transportation around the zoo.

5. Houston Zoo

The Houston Zoo is a 55 acre zoological park that houses 6,000 animals from 900 species. You can see Komodo dragons, jaguars, grizzly bears, mandrills, warthogs, red pandas and much more. The zoo has also invested $40 million in the 6.5 acre African Forest, where many giraffes, chimpanzees, white rhinos and cheetahs roam freely.