The closest packing of spheres in two dimensions has hexagonal symmetry where every sphere has six nearest neighbors. Double hexagonal close-packing corresponds to a ABAC stacking of such planes. Each atom has twelve nearest neighbors in dhcp.

Space group: 194 (P6₃/mmc)
24 symmetry operations:

1	x,y,z	identity
2	x,x-y,-z+1/2	C2 axis
3	-x+y,y,-z+1/2	C2 axis
4	-y,-x,-z+1/2	C2 axis
5	-x+y,-x,-z+1/2	6-bar axis|inversion center at 0 0 1/4
6	-y,x-y,-z+1/2	6-bar axis|inversion center at 0 0 1/4
7	x,y,-z+1/2	mirror plane
8	-x,-x+y,z+1/2	c-glide plane|translation: 0 0 1/2
9	x-y,-y,z+1/2	c-glide plane|translation: 0 0 1/2
10	y,x,z+1/2	c-glide plane|translation: 0 0 1/2
11	x-y,x,z+1/2	6-fold screw axis|translation: 0 0 1/2
12	y,-x+y,z+1/2	6-fold screw axis|translation: 0 0 1/2
13	-x,-y,z+1/2	2-fold screw axis|translation: 0 0 1/2
14	-x,-x+y,-z	C2 axis
15	x-y,-y,-z	C2 axis
16	y,x,-z	C2 axis
17	x-y,x,-z	3-bar axis|inversion center at 0 0 0
18	y,-x+y,-z	3-bar axis|inversion center at 0 0 0
19	-x,-y,-z	Ci: 0 0 0
20	x,x-y,z	mirror plane
21	-x+y,y,z	mirror plane
22	-y,-x,z	mirror plane
23	-x+y,-x,z	C3 axis
24	-y,x-y,z	C3 axis