Seven university students who jumped into the Brisbane River while on a party cruise have been given hefty fines.

The University of Queensland students sparked a police search when they jumped from a commercial boat at night into the Brisbane River, near St Lucia, last month.

The men were each given a $2,040 fine for breaching the Marine Safety National Law Act.

An eighth man was issued a warning for obstructing and hindering the investigation being conducted by the marine safety inspectors.