According to Walk Score, there is no "Walker's Paradise" in Jacksonville.  However, there are a few urban districts in Jacksonville that qualify as "Very Walkable" districts.

 Walkable Neighborhoods

Picture a walkable neighborhood. You lose weight each time you walk to the grocery store. You stumble home from last call without waiting for a cab. You spend less money on your car - or you don't own a car. When you shop, you support your local economy. You talk to your neighbors.

What makes a neighborhood walkable?

A center: Walkable neighborhoods have a discernable center, whether it's a shopping district, a main street, or a public space.
 

Density: The neighborhood is compact enough for local businesses to flourish and for public transportation to run frequently.

Mixed income, mixed use: Housing is provided for everyone who works in the neighborhood: young and old, singles and families, rich and poor. Businesses and residences are located near each other.

Parks and public space: There are plenty of public places to gather and play.

Pedestrian-centric design: Buildings are placed close to the street to cater to foot traffic, with parking lots relegated to the back.

Nearby schools and workplaces: Schools and workplaces are close enough that most residents can walk from their homes.

Streets Designed for Everyone

Complete Streets are roads designed for everyone who uses them, including bicyclists, pedestrians of all ages and abilities, and people getting on and off transit vehicles. These streets are:

Accessible: There are wheelchair ramps, plenty of benches with shade, sidewalks on all streets, etc.

Well-connected: Streets form a connected grid that improves traffic by providing many routes to any destination.

Built for the right speed: Lanes are narrow or traffic calming is in place to control speed.

Comfortable: Pedestrian medians at intersections, count-down crosswalk timers, bicycle lanes, protected bus shelters, etc. make the street work better for those outside of a car.

Left image: One-Mile Walk in a Compact Neighborhood
Right image: One-Mile Walk in a Sprawling Suburb

The images above compare the walkability levels in Nashville, Charlotte, San Francisco, New York and Boston with Jacksonville's.  Dark green represents maximum walkability and red represents auto dependency.

Walking Oasis in an Unwalkable City

Almost every city has walkable neighborhoods where it's possible to live a car-lite lifestyle. Here are a few examples of Walking Oases in cities with a low Walk Score.

San Marco, Jacksonville, Florida - Walk Score 80

Although Jacksonville is ranked #40 out of 40 with a Walk Score of only 36, San Marco, Jacksonville's second most walkable neighborhood, has a Walk Score of 80.

Based on the Piazza di San Marco in Venice, Italy, San Marco's short blocks and pedestrian-oriented design make it very walkable.
http://www.walkscore.com/rankings/walking-oases.shtml

San Marco Photo Tour: http://www.metrojacksonville.com/content/view/587/

Walk Score scorecard:

Walker's Paradise (dark green): 100 - 90

Very Walkable (light green): 89 - 70

Somewhat Walkable (yellow): 69 - 50

Car Dependent (red): 49 - 0

The top 20 walkable neighborhoods in Jacksonville, according to www.walkscore.com

rank, walk score, population, neighborhood name

 1. 88  3,373 Downtown Jacksonville
 2. 80  2,886 San Marco
 3. 71  1,762 Fairfax
 4. 71  9,754 Riverside
 5. 70  1,200 Southside (Southbank)
 6. 70    611 Normandy
 7. 68  3,523 Hogans Creek
 8. 67 10,392 Murray Hill
 9. 66  4,018 Regency
10. 64  6,055 Springfield
11. 62  2,891 Monterey (Arlington-East of University, South of JU)
12. 59    852 Brakridge (Southside Blvd. near Hodges)
13. 59  4,755 Lakewood
14. 58  7,789 Brentwood
15. 58  2,132 Pickwick Park (Mandarin)
16. 58  5,052 Arlington
17. 58  3,889 Arrowhead (Mandarin)
18. 56  4,495 Lakeshore
19. 56  5,825 Avondale
20. 56  5,296 Sans Souci

Walk scores of selected Jacksonville neighborhoods

40. 50 Panama Park
42. 49 Atlantic Beach
55. 46 Neptune Beach
56. 46 Southpoint
63. 45 Cedar Hills
72. 43 Baymeadows
74. 42 San Jose
99. 37 St. Johns Bluff
117. 31 Deerwood
142. 24 Mandarin
151. 21 Julington Creek
178.  7 Pecan Park

Statistical Data:

5% of Jacksonville residents have a Walk Score of 70 or above.

26% have a Walk Score of at least 50.

74% of Jacksonville residents live in Car-Dependent neighborhoods.

See where your specific home address ranks when it comes to walkability: http://www.walkscore.com