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.

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.

Coastal oceanographic processes present important differences to deep-water oceanography, resulting in higher prediction errors, where bottom topography exerts a strong control on wave/current/turbulence fields. These fields are modified by many additional factors that include interactions with coastal infrastructure, stratification, river discharges, and many non-linear effects such as breaking waves or nearshore circulation typical of shallow-water domains.

The special issue invites papers tackling simulations, observations, and analyses of coastal interactions, supporting the combinations of coastal observations (in situ and remote) and new modelling approaches (structured or unstructured grids) to reduce predictive uncertainties or to include new processes (interactions with groundwater flows, damping by biotopes, etc.). The special issue welcomes aggregation of data sets (e.g. different Sentinels or combinations with other satellites); new land boundary formulations; advanced assimilation or error bounding techniques; and, in general, original papers that contribute to the advancement of coastal oceanography. Papers proposing criteria to enhance applications or addressing the multiple scales in coastal processes, from storm events to decadal or climatic scales, are also welcome.

The special issue invites papers from recent and ongoing research projects dealing with green engineering for coastal zones and from EGU sessions in coastal oceanography and which can provide advancements in facing the many challenges experienced by present and future coasts. The wide range of possible topics is open to the interaction of nature-based solutions with coastal processes, uncertainties in coastal decision-making, and the role of operational coastal systems in reducing the growing risks in these areas. Contributions exploring the potential and currently open issues of non-linear response functions, support from artificial intelligence, or downscaled oceanographic projections are also covered.

The special issue will build upon a number of recent EU and international projects dealing with green engineering for coastal zones. Among them, there are many H2020 projects (e.g. the REST-COAST project; https://rest-coast.eu/) and an increasing number of special sessions dedicated to these topics (e.g. EGU but also Coastal Sediments 2023). The special issue is open and welcomes contributions within its scope.