The ornamental design for an expandablehikingdaypack, as shown and described.
FIG. 1 is a perspective view of an expandable hiking daypack showing the claimed design;
FIG. 2 is a top plan view thereof;
FIG. 3 is a left side elevational view thereof;
FIG. 4 is a front side elevational view thereof;
FIG. 5 is a right side elevational view thereof;
FIG. 6 is a back side elevational view thereof; and,
FIG. 7 is a bottom plan view thereof.
The broken lines depict portions of the article and form no part of the claim. The unshaded surfaces adjacent and inside of broken lines form no part of the claim.