The lipid liquid crystalline sponge phase (L3) has the advantages that it is a nanoscopically bicontinuous bilayer network able to accommodate large amounts of water and it is easy to manipulate due to its fluidity. This paper reports on the detailed characterization of L3 phases with water channels large enough to encapsulate bioactive macromolecules such as proteins. The aqueous phase behavior of a novel lipid mixture system, consisting of diglycerol monooleate (DGMO), and a mixture of mono-, di- and triglycerides (Capmul GMO-50) was studied. In addition, sponge-like nanoparticles (NPs) stabilized by Polysorbate 80 (P80) were prepared based on the DGMO/GMO-50 system, and their structure was correlated with the phase behavior of the corresponding bulk system. These NPs were characterized by dynamic light scattering (DLS), cryo-transmission electron microscopy (Cryo-TEM) and small angle X-ray scattering (SAXS) to determine their size, shape, and inner structure as a function of the DGMO/GMO-50 ratio. In addition, the effect of P80 as stabilizer was investigated. We found that the NPs have aqueous pores with diameters up to 13 nm, similar to the ones in the bulk phase.