The Seebek is a small stream in Hamburg, Germany, which flows from the lake of the Bramfelder See in a southerly direction.
After about 3 kilometres it discharges into the Osterbek. The stream is also known locally as the Grenzbach ('border stream' - it forms the boundary between Bramfeld and Barmbek in Hamburg) has a good water quality. In the 1980s the streambed was largely returned to a near-natural condition after it had previously largely degenerated into a concrete drainage ditch. Today the stream provides an outstanding habitat for many small animals. The process of renaturisation had not finished; since March 2005 NABU has run Project Eisvogel (Eisvogel = 'kingfisher') especially to improve the water flow through the Seebek.
Since 1959 Seebek has also been the name of an Alster steamer.