Despite the importance of mesoscale eddies, and other three-dimensional features discernable in numerical simulations of ocean circulations, to the understanding of oceanic heat transport and climate change, there are few dedicated three-dimensional visualization tools for scientists to use. This paper presents a framework for the visualization of three-dimensional (3D) ocean eddies in web browsers. The framework includes a feature-based eddy computation algorithm implemented by a standalone C++ program and a web graphics library-based 3D eddy viewer. Combining eddy extraction, tracking, query, and interactive visualizations in one workflow, the proposed framework is designed to facilitate the visual exploration and analysis of ocean eddies and thus help domain experts get more insight into the process of ocean circulation. In the framework, the feature-based algorithm significantly reduces the storage requirement of data and the rendering cost of visualization tasks by exploiting the coherence between consecutive data frames and focusing on just those regions of interest. The 3D eddy viewer presents eddy visualizations within a standard web browser, which enables the easy sharing of the tool and the results between scientific collaborators at different locations on diverse platforms without the need to install specialized software. In this paper, the general considerations in the design process as well as the technical facts of the framework, the application of the framework to a high-resolution regional ocean simulation, the general usage scenarios of the 3D eddy viewer and the user evaluation are discussed.