At the moment the zoo is undergoing some much need...

At the moment the zoo is undergoing some much needed updating to many of the enclosures so there are a few areas off limits to guests, however just the sheer size of our zoo still makes for a good walking adventure, we spent several hours. For the Eco/animal rights conscious here in Portland it should be noted that the Oregon Zoo's main focus is on conservation and education not display.
Pro tip: until the Washington Park route is reopened, avoid the zoo train. It is $4 each for a 15 minute loop that only goes to the elephant enclosures before turning around.