A nostalgic, painterly illustration in the style of classic American illustrators like Norman Rockwell or N.C. Wyeth. The scene depicts two young boys, one with a straw hat and the other with tousled hair, standing at the edge of a wide, shimmering river under a warm, late afternoon sun. In the background, a small, quaint steamboat is visible on the river, with the hazy silhouette of a frontier town nestled on the distant bank. The boys are looking intently at something just out of frame, conveying a sense of shared discovery and adventure. The color palette is rich with earthy browns, deep greens, golden yellows, and soft blues, creating a mood of hopeful innocence and a touch of mystery. The composition is balanced, drawing the viewer's eye to the boys' focused expressions and the expansive river landscape. The atmosphere is serene yet tinged with the excitement of an unfolding secret. The overall aesthetic should evoke the feeling of a timeless adventure story, with a soft, slightly diffused light.