This year, 2022, is the United Nations’ ‘Year of Groundwater’ (IGRAC 2021; Wikipedia 2022). In this year, the theme of World Water Day, 22 March 2022, is ‘Groundwater: Making the Invisible Visible’ (United Nations 2021). In addition to the special recognition that groundwater is receiving globally this year, 2022 is also the 30th anniversary of Hydrogeology Journal (HJ), providing another good reason to celebrate.

At the beginning of each year in the past, five articles that were published in HJ issues in the previous year were selected as Editors’ Choice articles. In order to celebrate and highlight groundwater, in the current special year and perhaps in future years, the HJ Editors—Martin Appold, Jean-Christophe Comte, Jean-Michel Lemieux, Rui Ma, Maria-Theresia Schafmeister and Clifford Voss—have decided to select ten articles as winners of the Editors’ Choice designation.

The 2021 Editors’ Choice articles are the ten articles that the editors especially like for a variety of reasons and consider to be exceptional. These have been selected from among the ∼140 unsolicited (not Special Issue) articles that were published in the 2021 issues of HJ.

While announcing the list of distinguished 2021 articles, the editors and HJ staff wish to thank those people who make HJ article publication possible by volunteering a significant amount of their time and energy. We much appreciate the continued and excellent support provided to HJ and its authors by the HJ associate editors, by the reviewers of HJ manuscripts, and by our abstract translation managers and their teams of helpers.

The Editors’ Choice articles are distinguished by a variety of positive attributes including: outstanding science, innovative approach, potentially important conclusions, important methodology, interesting field area or phenomenon, unusual topic, political/social/governance/historical/philosophical interest, challenging arguments, and more. The HJ editors believe that readers will find these articles to be especially interesting and valuable. These highlight the importance of groundwater in our world and how we humans interact with groundwater. The 2021 HJ Editors’ Choice winning articles are listed in Table 1, in order of appearance within the 2021 HJ issues.

Table 1 Hydrogeology Journal’s 2021 Editors’ Choice articles

Particularly in this ‘Year of Groundwater’, we invite you to download, read, and share all ten articles. These articles may well provide an excellent set of discussion topics for students in groundwater classes and for groundwater professionals at both formal and informal meetings and sessions.

To make it easier for readers to access all of these articles, Springer Nature will grant the ones that are not already freely available online (open access) with free online access for 8 weeks in 2022 following online publication of this announcement. The Editors’ Choice articles are also highlighted on the International Association of Hydrogeologists’ website (IAH 2022), via IAH social media, and in the IAH News and Information magazine.

Congratulations to all of these distinguished authors for producing such valuable and interesting articles!