Laboratory experiments were conducted in a wave flume on internal solitary wave(ISW)of depression and elevation types propagating over a submarine ridge in semicircular/triangular shape.Tests were arranged in series for combinations of submarine ridges of different heights and ISW of different amplitudes.The resultant wave motions were found differing from those of surface gravity waves.In deeper water,where an ISW of depression-type prevailed,the process of wave breaking displayed downward motion with continuous eddy on the front face of the ridge followed by upward motion to-wards the apex of the obstacle.Experimental results also suggested that blockage parameterζcould be applied to classify various degrees of ISW-ridge interaction,i.e.,ζ<0.5for weak interaction,0.5<ζ<0.7for moderate interaction,and0.7<ζfor wave breaking. Laboratory experiments were conducted in a wave flume on internal solitary wave (ISW) of depression and elevation types propagating over a submarine ridge in semicircular / triangular shape. Tests were arranged in series for combinations of submarine ridges of different heights and ISW of different amplitudes. The resultant wave motions were found differing from those of gravity gravity waves. In deeper water, where an ISW ​​of depression-type prevailed, the process of wave breaking displayed downward motion with continuous eddy on the front face of the ridge followed by upward motion to -wards the apex of the obstacle. Experimental results also suggested that blockage parameter ζcould be applied to all kinds of degrees of ISW-ridge interaction, ie, ζ <0.5for weak interaction, 0.5 <ζ <0.7for moderate interaction, and0.7 <ζfor wave breaking.