Environmental DNA (eDNA) has become a convenient monitoring method of biodiversity for past decade. In aquatic environment, most of study is focused on river and coastal area and oceanic survey is rare since water sampling is far more difficult in the ocean. However, ocean is as important as freshwater and brackish water area with marine resources. Thus, we tested methods to enhance collecting DNA from ocean by using 0.22 um pore size filter and adding four different materials (sediment, diatomite, zirconia beads, molecular sieve) during filtration. Thus, including standard method of using 0.45 um pore size filter, the experiment has six different experimental plots with five replicates of only 2-L filtration. The experiments were conducted in the Northern Pacific Ocean twice in summer and winter.