Te Awanui (Tauranga Harbour) contains two distinct basins the Katikati Basin in the north, and the Tauranga Basin in the south. The Katikati Basin is not well understood or researched as there is bias towards the Tauranga Basin due to dredging and port activities. This thesis investigated the Katikati Basin below the surface via a shallow seismic survey and above the surface using historic air photographs and hydrographic charts. No obvious faults were discovered within the seismic survey, therefore the faults found in the Tauranga Basin which are potentially associated with the Taupō rift may not extend into the Katikati Basin. The area surrounding the low gravity anomaly was analysed and there was no clear indication of a caldera therefore the seismic survey did not penetrate deep enough to reach the sediments associated with the low gravity anomaly. The historical air photographs and hydrographic charts showed that most of the changes to the geomorphology occur at the entrance where the tidal inlet has narrowed and deepened and at Waikoura Point on Matakana Island the spit tip changes shape and goes through periods of erosion and accretion especially during a triple-dip La Niña event of the El Niño Southern Oscillation Cycle. Unfortunately no coring samples were taken within the Katikati basin for this study, therefore the true thickness of the Holocene sediments were not determined however, other studies revealed Holocene sediments up to 20 m in depth which was the depth of this seismic survey therefore I am certain no Pleistocene sediments were reached. There is much more to be researched on the Katikati Basin and this thesis builds as a starting point.