Over the last 2 decades, studies have shown that the sea-surface microlayer covers large areas of the global ocean and, under certain conditions, can even form biofilm-like (and thus unique) habitats between the ocean and the atmosphere. Due to its recurrent biofilm-like features and unique position at the atmosphere–ocean interface, the microlayer is central to a range of global biogeochemical and climate-related processes, including marine carbon cycling, air–sea gas exchange, physical surface processes, and aerosol production. Despite the fact that processes occurring in and across the microlayer have received increasing attention during recent years, our knowledge about the microlayer remains rudimentary. New approaches and technologies have been developed to understand the formation and function of the microlayer on a mechanistic level. For example, the BASS (Biogeochemical processes and Air–sea exchange in the Sea-Surface microlayer; https://uol.de/en/bass) group has been funded to explore the significance of the microlayer as a bio- and photochemical reactor in an unprecedented comprehensive and interdisciplinary approach, and BASS findings will contribute to this special issue (SI). The purpose of the SI is twofold: (1) to present outcomes of a BASS mesocosm study and (2) to present further contributions on the microlayer from the wider research community based on field, mesocosm, modelling, and laboratory studies. This SI will bring together the latest scientific studies to describe the microlayer as an interface between the ocean and atmosphere across different disciplines.

Marine extreme events, encompassing phenomena such as storm surges, marine heatwaves, biogeochemical extremes, harmful algal blooms, jellyfish blooms, extreme storms, and even unique occurrences like medicanes (Mediterranean hurricanes), are becoming more common. These events have profound consequences for marine ecosystems, coastal communities, and global economies. Extreme sea level events, driven by intense storms and rising sea levels, can inundate coastlines, leading to devastating flooding and erosion. Marine heatwaves, fuelled by climate change, can trigger mass coral bleaching events, disrupting delicate marine ecosystems and jeopardizing the biodiversity that they support. Harmful algal blooms and jellyfish blooms, exacerbated by nutrient pollution and warmer waters, can lead to oxygen depletion, cause mass mortality events in various species, and pose risks to human health. The concurrence of oceanic and atmospheric extremes, marine and atmospheric heat waves, wind and wave extremes, harmful algal blooms, hypoxic conditions, and high-acidity events may lead to a nonlinear increase in environmental stress.

Addressing the impacts of these events requires a comprehensive approach, involving measures to mitigate climate change, improve coastal resilience, and promote sustainable marine management practices. A crucial aspect of addressing and mitigating the impacts of marine extreme events lies in deepening our scientific understanding of these phenomena and in establishing solid methodologies for defining climatological baselines and for extreme analyses in a changing climate. Scientific research plays a pivotal role in unravelling the intricate mechanisms behind these events, predicting their occurrence, and formulating effective strategies to manage and adapt to their consequences. By exploring the underlying causes, interactions, and feedback loops, scientists can provide invaluable insights that guide policymakers, communities, and industries in making informed decisions.

Over the past 25 years autonomous underwater gliders have progressed from experimental vehicles through scientific instruments to operational tools. Observations from gliders are now enhancing our understanding of physical, biogeochemical, and biological oceanographic processes. They represent a mature technology and complement traditional ocean sampling capabilities, especially for sustained real-time oceanographic measurements. They are now used as standard research tools in sustainable ocean observations and process studies, collecting measurements of physical, chemical, and bio-optical ocean variables. Underwater gliders have unique capacities to connect open-ocean and coastal processes and to sample the ocean at regional scales during multi-month missions. Gliders have been routinely deployed to monitor the ocean, for example monitoring continental shelves, boundary currents, and polar regions including in under-ice operations. More recently gliders have contributed to environmental hazard detection such as in the detection of marine heat waves and hurricane prediction.

This special issue has been stimulated by the International Underwater Glider Conference (IUGC) that was held in Gothenburg in June 2024, but submissions are open to everyone regardless of participation in the conference.

We invite papers advancing knowledge on the ocean's physical, biogeochemical, and ecosystem properties and processes by using underwater gliders and/or by their combined use with other observing platforms or numerical models. Contributions on technological aspects such as the development of glider sensors are welcome provided they include some ocean science advance.

Despite their socio-economic and environmental impacts, extreme events in the marine environment are generally poorly understood, simulated, or predicted. In particular, the dynamics of these events involve multiple temporal and spatial scales and can be driven by different mechanics and complex feedback involving the ocean and its interaction with the other spheres of the climate system. In response to climate change, the frequency and magnitude of these events could dramatically change, resulting in significant impacts on human life and property as well as on marine ecosystems. Hence, advancing our understanding of the dynamics leading to extremes in marine environments is crucial for improving their predictability, which, in turn, will help to achieve environmental and social sustainability. With this rationale, the special issue will focus on marine extremes at multiple temporal and spatial scales. Studies discussing ocean dynamics and air–sea interactions that can influence the evolution of marine extremes are particularly welcome; the inclusion of work using techniques ranging from in situ to remote-sensing observations and from numerical models to innovative artificial intelligence techniques (e.g. machine learning) is also encouraged. This diversity of topics will make for a highly multidisciplinary special issue, open to multiple applications in the field of marine extremes. Contributions related to the investigation of marine heat waves, marine storminess, storm surge and sea level rise, dense-water formation, deep-ocean extreme events, etc. are other examples of potential topics. The special issue has been stimulated by the EGU General Assembly 2023, session OS4.6, but all submissions on this topic are welcome, regardless of whether authors participated in the conference.

In 2024–2025 Ocean Science will be 20 years old, during which time it has been internationally at the forefront of high-quality, open-access, and open-peer-review publishing in our field of science. To celebrate this jubilee, we are publishing a special collection of “reviews and perspectives” papers, looking back at how ocean sciences have advanced over the last 20 years and looking forward to how they might advance over the next 20 years. The Ocean Science Jubilee special issue will be a compilation of influential papers across the broad range of ocean science topics covered by the journal. Accepted reviews and perspectives papers may also be included in the https://encyclopedia-of-geosciences.net/.

Submission of reviews and perspectives papers is open to everyone. We welcome the perspectives of early-career scientists. You do not have to be invited to submit a paper to the special issue. Reviews and perspectives papers are welcome on any topic and discipline within ocean sciences, as with any paper in Ocean Science. Manuscripts will undergo the usual rigorous and open peer review.