The general marine environment, namely the ‘wind-wave-current’ system, can develop into a typhoon, rogue wave, internal wave, or other extraordinary situations under specific circumstances, which significantly impacts offshore engineering structures and the safety of life and property in coastal areas. Given the characteristics of marine disasters in the South China Sea, we discuss the generation mechanism and propagation of internal solitary waves and their impact on marine engineering. In particular, we show that a large-amplitude internal solitary wave can excite a fully localized ‘rip’ region on the sea surface, called the ‘surface signature’ or ‘tide rip’ in the literature. We describe the reasons for these peculiar wave phenomena based on a newly developed model with full dispersion and weak nonlinearity. In the end, studies of internal oceanic waves are generalized to the atmosphere with particular attention to arched undular bores and the Kelvin wake.