There are a number of big questions that ongoing and planned surveys of neutral hydrogen (HI) in galaxies aim to address, including: - How do galaxies form and evolve and what role does neutral atomic hydrogen play in these processes? - What transformation processes in terms of accretion and gas loss occur in galaxy clusters? - How does the neutral hydrogen in galaxies relate to the star formation rate and how does this evolve with cosmic time? - How is mass (in the form of galaxies and clusters) distributed in the local Universe and how does the large scale structure influence the local velocity flow fields? In this proposal we aim to address many different aspects of these questions within the various sub-projects listed below which include both ongoing HI surveys as well as preparation for surveys on the SKA precursor instruments, MeerKAT, APERTIF and the JVLA. South African and Dutch astronomers are closely linked by their collaborations on these surveys. There are already active collaborations in various areas including software development, collaborative data analysis for projects already underway (e.g. CHILES, Coma Cluster), technical planning for data reduction, co-supervised students, etc. Further details are listed by sub-project in the main proposal.