This study aims to obtain cross-sectional views of clathrate-hydrate films each formed at the interface between a liquid-water phase and a hydrophobic hydrate-former phase. For this purpose, an experimental scheme was devised which permitted us to observe, through a high-resolution microscope, cross sections of a ring-shaped hydrate film formed over the surface of each discoid drop of HCFC-141b (CH3CCl2F)held stationary in a narrow space between two transparent plates filled with flowing, or quiescent, water. We found that the hydrate films, once exposed to a shear flow of water and then held in a quiescent medium of water, continued to thicken at a much higher rate than the films which had been held exclusively in a quiescent water medium since their formation. The former films kept their surface/internal texture much coarser. in the course of their thickening, than the latter films which showed very fine texture throughout. When continuously exposed to a steady water flow, the hydrate films kept their thickness constant. The steady-state thickness thus recognized showed a negative dependency on the flow velocity. A temperature rise. slightly exceeding the thermodynamic stability limit for the hydrate, caused each hydrate film once grown at a lower temperature to undergo crystal dissociation simultaneously throughout its thickness, in which numerous HCFC-141b droplets, a few micrometers in diameter, were evolved and migrated into the adjacent water phase.