Facing an era of rapid anthropogenically induced changes in the world oceans, ocean sound is now considered an essential ocean variable (EOV) for understanding, documenting and monitoring long-term trends in anthropogenic sound and its effects on marine life, biodiversity and ecosystem health. The International Quiet Ocean Experiment (IQOE) has identified two major research interests in the context of monitoring the distribution of ocean sound in space and time: i) estimating current levels and distribution of anthropogenic sound in the ocean, and ii) assessing trends in anthropogenic sound levels across the global ocean, and recommendations on ambient noise monitoring are also part of the EU Marine Strategy Framework Directive. To facilitate addressing these research foci by international collaborative research efforts, the OPUS (Open Portal to Underwater Soundscapes) data portal, which is currently being developed by the Ocean Acoustics Group of the Alfred Wegener Institute (AWI) in Bremerhaven, Germany, financially supported by the MAREHUB initiative, is envisioned to promote the use of acoustic data collected worldwide. To this end, an Ocean Sound Software for Making Ambient Noise Trends Accessible (MANTA) is being developed to generate standardized ocean sound level data products from passive acoustic recordings according to IQOE Guidelines, and will be distributed to data owners of underwater passive acoustic data worldwide. OPUS will accept MANTA-processed data (i.e., spectral sound pressure levels at millidecade/minute resolution) together with related metadata as they become available and make them accessible under customized licensing policies via a map- and time-based selection tool and shopping basket functionality. Data products including the compiled MANTA data, parameter-naming conventions, instructions for citing the data, and other information necessary to use the data according to FAIR standards will be regularly produced by OPUS.