Submissions are invited to the special issue of Journal of Marine Science and Engineering in the section Physical Oceanography. The issue tackles new frontiers in ocean observing and research in a broad context, underpinning the scientific knowledge, data and information, and applications and services. Contributions are expected to cover both in situ and remote sensing observations. The deadline for submissions is 5 June 2023, and manuscripts should be submitted online at mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form.