The Sanjay Gandhi Biological Park or the Sanjay Gandhi Jaivik Udhyan, popular as Patna Zoo, is located at Bailey Road in Patna. Considered the green lung of the city, it was established in 1969. Counted among the largest zoos in the country, it is home to approximately 800 animals of different species as well as numerous varieties of plants and trees. Besides, there is a big pond in the middle from which several jungle trails start, winding through the park. Together, they make this park an exciting and fun exploration experience for people of all ages.

The total area of the Sanjay Gandhi Biological Park is approximately 153 acre and it is virtually impossible to see the entire park in a single visit. The park is famed for being home to the royal Bengal tiger, besides species of colourful birds, chimpanzees, the one-horned rhinoceros, lions, giraffes, zebras, elephants, a variety of monkeys, deer and hippopotamuses etc. The total wildlife count includes 338 types of mammals, 355 species of birds, and 471 types of reptiles.

The park also houses an aquarium with over 30 species of rare fish. It is located in a pond on an artificial island. One needs to purchase additional entry tickets for the aquarium. Other sights of interest include a rose garden, herbal garden, a green house, a children's park, a lake, a tree house and a jungle trail. There is a snake house as well with around 30 varieties of serpents. Separate museums for bats, turtles and owls are also in the offing. Visitors can also go around the park in a five-compartment toy train that runs at regular intervals. There is also the option of boating in the pond here.