Where we're in a different dimension

''Those kinds of experiences are not all that thick on the ground.'' Roy Walker describes his discovery of swimming, and seeing, underwater - an experience that waited until his late 30s, early 40s - as the best kind of ''visual shock.''

To find suddenly a new, unfamiliar ''world'' and to be able to observe it with something like a child's eye, for the first surprised time, is providential for an artist, particularly when he has already spent years developing stylistic resources that are able not only to compass the fresh view but to be stretched by it.

Walker has overcome a terror of water, and in learning to swim has found he can do it (unconventionally, perhaps) more easily under than on the surface. Someone suggested that goggles might make his subaqueous explorations less trying to the eyes - and it was then that the visual astonishment of water-liberated figures, of forms moving in this strangely private, enclosed realm of people weightless, and even transformed to an unexpected beauty, opened to him. His fascination has been so strong that he has produced many drawings and a number of finished watercolor and ink paintings on the theme. He foresees its interest lasting a long time for him. ''Push Off'' is a fine example.

This is not only a painting of underwater swimmers he has observed (he watched a mother and daughter one time training together; they swam in an extraordinary unison), but also an identification with the very feel of pushing away from the end of the pool: It is his translation, into pictorial terms, of launching himself, as if he were leaping upward from the moon, into the supportive, resisting liquid. He has pictured the strangely disorienting underwater world (where people ''In spacious Regions seem'd to go/As freely moving to and fro,'' in the words of Thomas Traherne's rather mystical poem ''Shadows in the Water'') where we find ourselves in a different dimension, in which directions take on ambiguous meanings, and we are freed to a degree from the earth pull we take so much for granted.

These figures might be astronauts as easily as swimmers, though Walker has also skillfully suggested the weird, watery distortions imposed on the figures by light filtering, reflecting, and flickering through the water: a scattered rather than a directional light. The transparency and fluidity of watercolor have proved the ideal medium for conveying this enclosing, silent waterscape - the play of shadows over every surface contained within it, the swaying waves above the swimmers.

The artist finds there is also an element of humor to the way in which, as they make the transition from human to temporary fishhood, swimmers seem partly left behind in the upper air, partly entered into the new world: The ceiling of water, the skin through which they break, separates one sphere from the other (and one part of the swimmers' physique from another) in an almost arbitrary way and adds to the surreal quality it is not hard to perceive in these paintings. The swimmers' goggles only add to their slightly nonhuman appearance: beings from another planet.

Roy Walker also practices drawing from ''life,'' directly from the model (though his swimmers are all done from memory), describing this as ''a kind of regime to stretch myself.'' Something of the way he uses a continuous, unbroken line of unvarying thickness to trace, or track, the ''landscape'' of a figure can be seen in the two figures cavorting in ''Push Off.'' His line not only describes with a kind of strict looseness the contour of limbs, feet, hands, neck, torso, but also moves over what he terms the ''inner landscape'' of figures. Above all it explores - in the two-dimensional limits of a flat sheet of paper - the stretching of a figure into and out of ''space'': its third dimension.

When drawing from life, he works ''in a high state of intensity,'' recalling something he once heard about the training of Japanese archers. ''They become the arrow,'' he says. ''I become the point of the pen.''

He greatly admires Rodin's drawings, with which the French sculptor captured the movements of dancers - the nearest thing, perhaps, to swimmers in our accustomed air-world. An ambition would be to achieve the vigor, ''the whiplash energy,'' of Rodin's line. The liberating influence of swimming, of moving underwater - which to Roy Walker is such a vivid discovery - is pushing his art effectively in that direction.

We want to hear, did we miss an angle we should have covered? Should we come back to this topic? Or just give us a rating for this story. We want to hear from you.