This is a great Zoo, they have wagons that you can use or bring your own.  Good to go in the morning when you can see the elephants getting a bath.  Less crowded in the morning hours.

Roger Williams Park Zoo is home to hundreds of rare and fascinating animals from around the world including polar bears, snow leopards, moon bears, giraffes and elephants all in naturalistic settings. The zoo's population numbers over 1000 animals, with some 139 different species on display at any given time