Established in 1933, the Permanent Service for Mean Sea Level (PSMSL) has been responsible for the collection, publication, analysis and interpretation of sea level data from the global network of tide gauges. It is based in Liverpool at the National Oceanography Centre (NOC)

The PSMSL is a regular member of the ICSU World Data System. Funding for the PSMSL comes from the Natural Environment Research Council (NERC).

The head of the PSMSL is Elizabeth Bradshaw.