Child's Aquatic Vehicle

FIG. 1 is a front perspective view of an ornamental design for a child's aquatic vehicle; FIG. 2 is a front view thereof; FIG. 3 is a rear view thereof; FIG. 4 is a left view thereof; and, FIG. 5 is a top view thereof. The broken lines shown in the figures illustrate portions of the child's aquatic vehicle that form no part of the claimed design.