Semi-diurnal variations of the fluid discharge from the deep sea bottom were found at the water depth of 1360 m, Suiyo Sea Mountain, Ogasawara, Japan, by using newly developed automated seepage meters. A temperature depth profile of the pore water under the seabed also suggests heat is transported due to advection by the upward fluid flow. Upward fluid fluxes estimated from the type curve method using heat conduction-convection theory agreed well with the values obtained by automated seepage meter.