This paper describes close-packed liquid-filled tunable microlens arrays for optical devices such as integral imaging systems. These lenses are simply composed of poly(dimethylsiloxane) (PDMS) microchannels. Applied pressure deforms the top membrane of microchannels to form convex lenses. These lenses have three advantages: (i) Uniform deformation by pressure-driven actuation, (ii) Adjustable optical characteristics without patterned electrode, (iii) High-density integration of tunable microlenses. We fabricated three types of lenses: 'Honeycomb', 'Ladybird' and 'Spiderweb' as close-packed structure and showed that the 'Spiderweb' type packing is the most suitable for close packing. We believe that these lenses can be applied to optical applications such as 3D displays based on integral photography.