A large lion eyes you intently, maybe hungrily, across what appears to be an open, grassy field. She rises from her rest, and one paw after another, slowly approaches.

Unsettling. Even when you know you really are quite safe.

A walk in the midst of wildlife is one of the many illusions that have earned Seattle's Woodland Park Zoological Gardens distinction as one of the nation's most innovative zoos. Visitors view the animals in realistic settings, but rarely see the protective barriers.

The lioness roams a portion of the zoo's five-acre African Savanna, a wonderful re-creation of Africa's rolling grasslands. In their native land, the lions, giraffes, hippos, zebras and other wild animals live in natural but uneasy proximity. At the zoo, they live in proximity, too, but nobody gets to dine on a fellow resident.

The scene is like something out of a safari movie. On a hillock stands a pair of giraffes. Zebras browse beside them, while exotic crowned cranes, the tall African birds, strut past. And the lions watch from the rocks behind, seemingly ready to pounce if they get a chance. But carefully concealed gullies separate these predators from the less-aggressive beasts and keep all of the animals away from the human sightseers.

The illusion succeeds very well, and that is much of the fun of this zoo. You can easily imagine you are on a foot safari in the wild, and your photos could convince others that you were.

It takes only a few minutes to realize how unusual the African Savanna exhibit really is. In many zoos, lions are kept in the lion house and the giraffes in the giraffe pens. At the Woodland Park zoo, however, the animals are grouped together as they are in nature.

Isolating species "goes against the grain of nature," says zoo spokesman Henry Klein, assistant curator for education. "It makes more sense to use nature, and it's more interesting to the general public." It is a philosophy other zoos have begun to adopt.

This exciting 90-acre zoo is located on the western edge of Woodland Park in a comfortable residential neighborhood about six miles north of downtown Seattle (about 30 minutes by city bus). It dates from 1904, but only in the last decade has it begun to acquire a reputation for excellence.

A master plan adopted in 1976 set the goal of redesigning the zoo into 10 "bioclimatic" zones, such as the African Savanna, each representing a different part of the world. About a third of the plan has been completed, although progress was slowed by the last recession and the failure of a recent bond issue for city park improvements.

Zoo officials are hopeful, nevertheless, that a major fund drive, now underway, will bring the $30 million to $40 million needed to complete the plan, although that is still 10 to 15 years away. Klein doesn't hesitate to point out that much of the zoo remains antiquated, although it is one of the few U.S. zoos to receive a "No. 1" rating from the Humane Society of the United States for what it has accomplished so far.

"It is doing most of what a zoo is supposed to be doing," says the society, "and doing it very well."

Re-creating natural environments has called for a great deal of ingenuity, and this was particularly true for the African Savanna, which won the 1981 "Exhibit Award" for authenticity from the American Association of Zoological Parks and Aquariums.

Some of the African grass plants, which grow up to eight feet tall, would not easily survive even one of Seattle's normally mild winters. So the zoo found lookalike substitutes, and they have worked well with, perhaps, only one unexpected problem: Visitors sometimes complained that the zoo was lax in cutting its grass. Now a discreet sign alongside the path advises: "Be assured these are not weeds."

The path is laid with reddish cinders to duplicate the soils of East Africa. A rustle in the tall grass alongside is likely to startle, but it's probably a flock of blue guinea fowl. They roam freely throughout the savanna, clucking loudly as they pop in and out of sight at any moment.

The terrain was carefully contoured into rolling hills and small ravines to resemble the savanna. But the layout also gives the animals hideaways where they can vanish from view if they want to avoid humans, or even each other. In a sense, they get to relax offstage occasionally.

The animals' grazing range also was raised to a plateau above the eye level of spectators, so the animals peering out from the advantage of height would not feel quite so surrounded. The result, says Klein, is that they "seem more active, less bored, and they are breeding better." The plateau also hides visitors from each other, enhancing the wilderness impression.

Some zoos boast of their fancy structures. Seattle's zoo is going to great pains to bury its. In the savanna, the stables for zebras and the springboks (an antelope) are cut into a hillside and roofed with sod. Only the giraffe house could not be buried, because it had to be so tall. So it was placed outside the exhibit in a grove of trees, and the giraffes must be escorted to and from the exhibit in a twice-daily parade.

Zoo officials count themselves lucky that Seattle's mild year-round climate limits the need for extensive winter structures, but they have provided some extras for nippy days. Those solid-looking rocks on which the lions gather are actually artificial, and they are lined with built-in electric heating coils.

Some of the largest boulders along the savanna paths are hollow and double as animal shelters. Inside are heat lamps.

Visitors don't see these devices and probably wouldn't know they were there unless told. Instead, a walk through the savanna is a constant unfolding of seemingly natural views stretching before you around each curve. It is this sense of open space at Woodland Park that impresses most. There is a freedom of movement not usually associated with zoos. The animals range widely under what certainly could be a beautiful African sky. And, in fact, so do you.

Sometimes along the path you are the watcher, but sometimes the watched. Glance over your shoulder, and you may discover a stalking lion with you in its eyes.