Buizengat is a historic inner harbour in the eastern part of Rotterdam, dating to at least the late 17th century.

Originally known as "Spuiwater," it was constructed as a sluice outlet for the Oude Haven and quickly became associated with the herring fishing vessels — known as "buizen" — that once made it their home port.

The name "Buyssche Gadt" appears in archival records as early as 1698. The waterway connects to both the Boerengat and the Nieuwe Maas via a sluice canal. Today's Buizengat represents roughly one-third of the original sluice-water surface the city once used.

The harbour is navigable by small recreational boats, passing under lifting bridges as it transitions from the more historic Boerengat into its own somewhat more industrial character.

The municipality of Rotterdam, together with Rijkswaterstaat, has added approximately 1,000 square metres of floating greenery to the waterway as part of ongoing improvements to this historic basin in the Kralingen district.