No other medium has watercolor’s blend of luminosity and directness, and none requires so sure and responsive a touch. With larger watercolors, it becomes even more difficult to maintain a spontaneous effect. Big dimensions, however, obviously present no problem for Susan Shatter, whose immense landscapes and seascapes at DFN Gallery show both a formidable technique and a remarkable freshness. These works are confined to two motifs: Southwestern desert canyons and rocky Maine shores, and they contain virtually no trace of human, animal, or plant life. Because of their downward point of view, only small strips of sky occasionally appear at their upper edges. This concentration on the elemental, though, allows a vital, organic exploration of whole environments.

Ms. Shatter works from preparatory studies, but even her largest watercolors have the fluidity and breadth of first-hand responses. Forms are confident and hues clear — even in shadows with multiple layers of color — so that the great masses in the 6-foot-wide “High Desert I” (2005) sort lucidly into buttes and valleys spreading below one’s gaze. Orange and burnt sienna washes become a dramatic projection of rock in the foreground; its sides drop hundreds of feet to a rocky plain captured in darker washes of ultramarine, cerulean, and crimson. Scarlet ranges of hills and green and pink valleys draw the eye, point by point, to the horizon of this inhospitable world awash with color.

The depiction of vast, exotic spaces in this watercolor and in its only slightly smaller companion “High Desert II” (2005) is dazzling, and yet I prefer the dramas of her seascapes. In four large works in the gallery’s main space, sea and rocks occupy approximately equal amounts of paper, so that their compositions resound with the penetrating entanglement of the two. In works like the nearly 10-footwide “Crash” (2006), Ms. Shatter maximizes the contrast of fluid and faceted worlds: the translucent depth of the sea, rolling with blues and greens and crested with white ribbons of foam; the prismatic array of warm, compact lights and darks. The visual collision invokes the sensation-saturating rhythms of the real thing — so startlingly that one struggles to remember it’s only diluted pigments on paper.

Don’t overlook several small seascape studies in the gallery’s viewing room. These have every quality of the larger ones except the physical dimensions. If they’re less impressive technically, they show a wonderfully intimate, one-to-one correspondence between nature’s gestures and the artist’s responses, with that immediacy available only in watercolor.

If Ms. Shatter pursues wild expanses, Stuart Shils mines the nuanced and diminutive.

His recent monotypes at Davis & Langdale depict scenes from his hometown of Philadelphia as well as from trips to Ireland, Israel, Vermont, and Indiana. But like his oil paintings, they explore a relatively narrow niche: small, simplified compositions rendered in evocative, atmospheric strokes of color. All these prints measure about 6 inches square and date from this year.

Mr. Shils’s painterly textures would seem ideally suited for timeless subjects, but in “From Guy’s Balcony, Ahad Ha’am Street #1,” he vigorously tackles the crisp geometry of a modern, multistory Tel Aviv building. Here, hues energize a straightforward composition. A vibrant deep blue sounds the shadowy cleft between two buildings, one of them partially covered by a lighter gray that has just the right pressure of a shadow cast by the other building. Above them, Mr. Shils’s masterful textures — brisk, but sensitively tuned — lends the sky a humming depth.

As is sometimes the case with his paintings, Mr. Shils’s monotypes can be over-reliant upon such textures. For instance, the approximated shapes and location of colors in “From Emek Ha Matzieva” leads to a certain slightness of effect, as if the artist were content with just invocations of atmosphere.

Hanging next to it, however, “Along 33rd Street, Strawberry Mansion, North Philly,” has a brightness of rhythm to match its hues. Here, colors not only shift restively about — moving in this case from the vibrant orange-reds of sunlit brick façades to the sky’s spacious cobalt blue — but also build with intense, concise sequences. After the march of orangered brick, a shadowy violet cuts back abruptly across the buildings above the punctuating note of a tree. A deep blue diamond of roof, weighted by its location and color, provides the essential separation of buildings and sky.

On another wall, “Rooftops, Night Descending” is a true gem. With Turneresque élan, Mr. Shils places a building in the mid-distance, so that its front, illuminated by late-afternoon sun, glows against the contrasting darks on its every side. A particularly dark blue plunges in space to one side; in it, a slender tower rises, the print’s lightest note, addressing us from afar. Small ragged notes of white — bits of the paper showing between strokes — attest to the energy of ink application, matched in this case by a dynamic conception of the subject.

Shatter until November 25 (210 Eleventh Ave., between 24th and 25th streets, 212-334-3400);

Shils until November 18 (231 E. 60th St., between Second and Third avenues, 212-838-0333).