The ornamental design for a “beach towel,” as shown and described.
FIG. 1 is a perspective view of a beach towel showing my new design;
FIG. 2 is a top plan view thereof;
FIG. 3 is a bottom plan view thereof;
FIG. 4 is a front elevational view thereof, the rear elevational view being a mirror image thereof;
FIG. 5 is a right side elevational view thereof; the left side elevational view being a mirror image thereof; and,
FIG. 6 is a perspective view thereof as held by a central loop.
The broken line environmental structure is for illustrative purposes only and forms no part of the claimed design. The surface pattern shown fragmentarily on the beach towel in the drawing views is understood to be repeated uniformly throughout the top and bottom surfaces.