The 10-Year Anniversary of Parcels

Project- and teameader Erik van Sebille cuts a cake with the text Parcels on it.

Last month, there was cake at IMAU because Parcels turned 10 years old! Parcels is a highly customisable Lagrangian simulation framework for tracking passive and active particulates such as water, plankton, plastic, icebergs, and fish using data from flow datasets. The open-source development of Parcels is led by Erik van Sebille and his team at IMAU.

On 29 September 2015, postdoc Michael Lange pushed the first commit (b2ae2fd) to GitHub. Parcels has come a long way since then: more than 270 articles have been published using Parcels, on topics ranging from ocean current transport analysis, plastic pollution mapping, and fish larvae tracking, to more niche applications such as iceberg melt and AUV steering, to winds on Jupiter (the planet) and the behaviour of tuna (the fish).

To celebrate this 10-year milestone, we held a workshop-conference-hackathon-party in Utrecht from 1–3 October 2025. More than 50 people attended in person, and another 60 joined online. During the event, attendees showcased how Parcels is used by different researchers and learned from each other. There were workshops, tutorials, hackathons, and a mini-conference.

A group photo of the attendees of the workshop-conference-hackathon-party in Utrecht from 1–3 October 2025.

Attendees were also able to sneak a peek and test-drive the first (pre-)release of the new Parcels v4, a major, radical overhaul of the Parcels codebase. Parcels v4 is even more powerful and versatile, including support for unstructured grids!

The event ended with a festive Jeu-de-Boules tournament (relevant because of the particle–particle interaction) on Friday evening. This was to celebrate how far we’ve come and to thank everyone for their contributions and engagement over the years.

Following the Parcels event, we’ve now established the Computational Lagrangian Analysis and Modelling (CLAM) community as a space where Lagrangian modellers can interact, discuss their ongoing research, explore new collaborations, and shape future community projects.

As part of the 10-year anniversary, the Parcels homepage has moved from oceanparcels.org to parcels-code.org, dropping the word “ocean” from its name. We did this to explicitly highlight that Parcels can also be used to track virtual particles in the atmosphere, in ice sheets, and in any (geo)physical flow. The future for Parcels is bright!