In this talk, we consider the joint effects of tidal and steady currents to investigate internal wave generation and propagation, suggesting that it is an efficient way for energy cascade from large-scale motions to turbulence. Two hotspots of internal waves around the world are investigated in this research: the continental shelf off the Amazon River mouth and the northeastern shelf of the South China Sea. Field measurements, satellite observations and numerical modelling are used in this study. In the Amazon Shelf, the joint effect of the North Brazilian Current and tidal flows interprets the generation of along-shelf propagating internal solitary waves. In the northern South China Sea, our observations show that such the effect induces the generation of more small-scale internal solitary waves locally, making the internal wave in the northern South China Sea to be unpredictable. Observations and numerical simulations indicate the tidal generation of internal lee waves over small-scale bathymetry, which plays an important role in a rich generation of small-scale internal waves and further enhances ocean mixing.