Colchester Zoo has been ranked as the eighth best in Europe, according to reviews compiled by users of TripAdvisor.
The attraction was also named the second best in the UK, beaten only by Chester Zoo, which came sixth in Europe. The ranking is based on more than 1,000 reviews.
UZ zoos also outperformed those in every other country, with eight in the top 25 from around the continent.
The top European zoo was Loro Parque at Puerto de la Cruz on Tenerife while the best world zoo was Henry Doorly Zoo, at Omaha in Nebraska, USA.
James Kay, Tripadvisor spokesman said: "These awards are based on the millions of reviews and opinions written by our global community of travellers.
"So if you're looking for some inspiration for a great family day out, the UK winners are a great addition to your summer holidays hit list."
Top 10 zoos in the UK, according to TripAdvisor
- Chester Zoo, Cheshire
- Colchester Zoo, Essex
- Paignton Zoo Environmental Park, Devon
- Folly Farm Adventure Park and Zoo, Begelly, South Wales
- Blackpool Zoo
- Durrell Wildlife Park, Trinity, Jersey
- Cotswold Wildlife Park and Gardens, Burford, Oxfordshire
- Knowsley Safari Park, Liverpool, Merseyside;
- South Lakes Safari Zoo, Dalton-in-Furness, Cumbria
- Blair Drummond Safari and Adventure Park, Stirling, Scotland.