In this study, a 3D virtual reality and visualization engine for rendering the ocean, named VV-Ocean, is designed for marine applications. The design goals of VV-Ocean aim at high fidelity simulation of ocean environment, visualization of massive and multidimensional marine data, and imitation of marine lives. VV-Ocean is composed of five modules, i.e. memory management module, resources management module, scene management module, rendering process management module and interaction management module. There are three core functions in VV-Ocean: reconstructing vivid virtual ocean scenes, visualizing real data dynamically in real time, imitating and simulating marine lives intuitively. Based on VV-Ocean, we establish a sea-land integration platform which can reproduce drifting and diffusion processes of oil spilling from sea bottom to surface. Environment factors such as ocean current and wind field have been considered in this simulation. On this platform oil spilling process can be abstracted as movements of abundant oil particles. The result shows that oil particles blend with water well and the platform meets the requirement for real-time and interactive rendering. VV-Ocean can be widely used in ocean applications such as demonstrating marine operations, facilitating maritime communications, developing ocean games, reducing marine hazards, forecasting the weather over oceans, serving marine tourism, and so on. Finally, further technological improvements of VV-Ocean are discussed.