Dogs have more chances to sniff butts in Portland than anywhere else in America.

That's not politics, it's math: With 33 public off-leash areas, Portland has the most dog parks per capita of any large U.S. city.

But not all dog parks are created equal. With the help of a tireless Australian shepherd named Scout, we spent a very rainy week exploring 10 of the largest, most singular dog parks in town. As we learned during the course of our visits, Portland's off-leash spots can run the gamut from "ill-marked muddy field" to an impressively expansive nature park on the shores of two rivers.

We ranked the parks giving equal weight to amenities, social factors, and design and terrain. Here's what we found, from best to worst.

(The Ross Dog Park, Abby Gordon)
(The Ross Dog Park, Abby Gordon)

1. Thousand Acres (Sandy River Delta Park)

Crown Point Highway, Troutdale. 1,400 acres, all off-leash except the Confluence Trail and parking lot.

In Portland's swampy northeastern reaches, Thousand Acres is dog Shangri-la. Expect a trail leading to a lazy river, a wild abundance of plant life and a Maya Lin-designed bird blind. Consider it less a city park than an off-leash hiking trail.

Bonus for dogs: Racing other dogs to fetch sticks thrown into the shallow waters of the Sandy.

Drawbacks: You have to drive to Troutdale. Also, there's no escaping the mud. Bring towels.

(The Ross Dog Park, Abby Gordon)
(The Ross Dog Park, Abby Gordon)

2. Sellwood Riverfront Park

Southeast Spokane Street and Oaks Parkway. 8 acres, with off-leash only on the main lawn.

At this picnic-friendly park under the Sellwood Bridge, the off-leash area is a large lawn populated by goldendoodles and chatty owners, but the trails along the waterfront can feel surprisingly woodsy. Come here if your dog wants to swim, but you don't want to drive to Troutdale.

Bonus for dogs: Striking regal poses against the backdrop of the Willamette River with downtown in the distance.

Drawbacks: The off-leash area doesn't include the waterfront. Few dog owners heed this.

(Dog Bowl, Abby Gordon)
(Dog Bowl, Abby Gordon)

3. Ross Dog Park

5167 NE 15th Ave., Vancouver, Wash. 8 fully fenced acres.

Yes, it's in Vancouver. But always-busy Ross puts Portland's fenced parks to shame. Iit's huge, with a half-mile of jogging trail around a lawn dotted with trees.  You're never far from a trash can or plastic-bag dispenser, and the park's water spigot saves you the trouble of bringing a bottle. Like Portland's Normandale Park, Ross offers a separate fenced area for small dogs, ensuring a Yorkie can chase balls without being pushed around by a German shepherd.

Bonus for dogs: Running wild with the dozens of other herding dogs that always seem to show up here.

Drawbacks: You have to drive to Vancouver.

(The Ross Dog Park, Abby Gordon)
(The Ross Dog Park, Abby Gordon)

4. Laurelhurst Park

Southeast Cesár E. Chávez Boulevard and Oak Street. 31 acres. Off-leash dog run abutting Oak Street.

Its grassy hillocks, duck pond and shaded nooks make Laurelhurst Park Southeast Portland's collective backyard. As with a lot of backyards, dogs get free run of the place. But the paved, winding paths and art installations make it as pleasant for people as for pups.

Bonus for dogs: Chasing the ducks, jumping in the duck pond, watching the ducks swim in the deep water and daring them to come back to the shallows.

Drawbacks: There are fewer dog pals than at other parks. The off-leash area technically doesn't include the duck pond.

(Dog Bowl, Abby Gordon)
(Dog Bowl, Abby Gordon)

5. Mount Tabor

6336 SE Lincoln St. 190 acres. 4-acre off-leash area at the bottom of the hill on the south side.

The hillside dog park at the bottom of Portland's most famous cinder cone is fenced just enough that you won't worry when your dog immediately sprints out of view up the park's winding dirt path. While you can't play fetch, dogs do seem to enjoy running up and down the steep inclines. On nearby trails, you can watch certain dedicated humans doing the same thing.

Bonus for dogs: Running ahead along the trails and hiding in the bushes until owners catch up.

Drawbacks: Parking is sparse near the dog park.

(The Ross Dog Park, Abby Gordon)
(The Ross Dog Park, Abby Gordon)

6. Chimney Park

9360 N Columbia Blvd. 5.5-acre fenced dog park.

Named after the giant incinerator whose fires once burned here, this isolated St. Johns spot is now a busy, sociable dog park. The sparsely wooded dog park is both vast and fully fenced, great for high-energy dogs with less-than-reliable recall.

Bonus for dogs: Being able to run to the far edges of the park without being called back.

Drawbacks: The ground is pretty muddy in wet weather.

(The Ross Dog Park, Abby Gordon)
(The Ross Dog Park, Abby Gordon)

7. Fernhill Park

6010 NE 37th Ave. 26 acres, with a large off-leash area.

At the eastern edge of Concordia, Fernhill Park has a little something for everyone. Near tennis, horseshoes and softball, the off-leash area is large and varied. Dogs can run, chase, fetch and train easily here.

Bonus for dogs: On this occasion for Scout, it was a round of Frisbee with a very fast Jack Russell terrier.

Drawbacks: The park has no fence and is very close to a busy street. For trusted dogs only.

(Dog Bowl, Abby Gordon)
(Dog Bowl, Abby Gordon)

8. Portland International Raceway

1940 N Victory Blvd. 300 acres, with a 3-acre off-leash space.

When cars aren't whizzing around the track, dogs are free to race around on an endless grass field. But bring waterproof shoes. The raceway is located next to wetlands, which turn the field to muck.

Bonus for dogs: The only things to do here are running fast and playing fetch, but these happen to be two of Scout's favorite activities.

Drawbacks: Other than open space, there's not much else.

(The Ross Dog Park, Abby Gordon)
(The Ross Dog Park, Abby Gordon)

9. Lents Park

5208 SE 88th Ave. A small off-leash area in the corner of a 38-acre park.

Lents Park's off-leash dog area is a small, uneventful space in the corner of the park's grassy expanse. On our visit, no other dogs were present. But we did appreciate the water spigots allowing worn-out pups to catch a sip.

Bonus for dogs: It's easier to focus on fetch when there are no other doggies around to distract you.

Drawbacks: The park was empty and small.

(The Ross Dog Park, Abby Gordon)
(The Ross Dog Park, Abby Gordon)

10. Dog Bowl

3100 N Willamette Blvd.

On Skidmore Bluffs best known for romantic views at sunset, the Dog Bowl is an ode to steely pragmatism—an undeveloped lot locals decided might as well be a dog park. There's an extremely muddy open area where you can play fetch. And sometimes, that's all you need.

Bonus for dogs: The sticks here are apparently very interesting. During fetch, Scout kept bringing me new ones instead of fetching the one I'd thrown.

Drawbacks: Street parking. No trash cans. No fence. The park is accessible only by climbing down a steep, slick path.

(The Ross Dog Park, Abby Gordon)
(The Ross Dog Park, Abby Gordon)