Seismic interpretation is an important step in building subsurface models, which are needed to efficiently exploit fossil fuel reservoirs. However, seismic features are seldom unambiguous, resulting in a high degree of uncertainty in the extracted model. In this paper we present a novel system for the extraction, analysis, and visualization of ensemble data of seismic horizons. By parameterizing the cost function of a global optimization technique for seismic horizon extraction, we can create ensembles of surfaces describing each horizon, instead of just a single surface. Our system also provides the tools for a complete statistical analysis of these data. Additionally, we allow an interactive exploration of the parameter space to help finding optimal parameter settings for a given dataset.