Introduction: The varied ways of getting there This book both celebrates and makes visible the diverse processes that lead to a Doctoral Thesis. We did this by inviting the authors to write so-called “Process Summaries” i.e. short descriptions of the process that ultimately led to their Doctoral Thesis. While writing those summaries, we advised the authors to reflect the most rewarding and challenging parts of the process and to consider what kind of twists and turns the journey entailed. We also asked the authors to think what kind of advice they would like to give now to themselves when they were just starting their thesis work. The result is this collection of Process Summaries and related official Thesis Abstracts. Together, the summaries indicate that completing a Doctoral Thesis is not just one process, but several processes brought together — often along a long and winding road with unforeseen uphills and downhills. Despite this, the Thesis itself describes mainly its scientific contribution, and the related learning and collaborative processes are usually referred to only in a concise and declaratory manner. While this is understandable, it also partly misses the point: as the Process Summaries remind us, the Doctoral Thesis is very much about the diverse ways of “getting there”. By making visible these diverse journeys we feel that this book makes three important contributions. First, the Process Summaries remind us about the importance of collaboration, collegial support, and peer learning — a recurring theme throughout this book. Second, the summaries show very clearly that there is no one “correct” way of carrying out doctoral research, but each path is unique. Thirdly, we hope that the stories documented in this book provide insights and even inspiration for those currently planning or being on the journey of getting there. In that journey, the authors’ encourage us to be active, curious, and brave, to explore and enjoy and, ultimately, to trust in the process and trust in yourself. This book includes a selection of Doctoral Theses that have been completed in the field of water and environmental engineering at Aalto University and its predecessor Helsinki University of Technology from year 2002 until 2022. This, way, the book also celebrates the 20th Anniversary of our Water Building, located at Tietotie 1E in Otaniemi. Thank you to all the contributors! Marko, Maija and Heidi