Instrumentation advancements in the last decade have produced a deluge of ocean sonar data. These data provide opportunities to study the marine ecosystems at unprecedented spatial and temporal scales. However, to date, these data remain significantly under-utilized, mainly due to the lack of data interoperability and scalable analysis workflow. We address these challenges by developing an open-source Python package, echopype, which defines an interoperable netCDF file format and leverages the power of Xarray and Dask for explicit and efficient sonar data analysis in the Jupyter environment.