Detailed seabed bathymetric data are needed to better understand our marine environment because models of seabed morphology derived from these data provide useful insights into physical processes that act on the seabed and the location of different types of seabed habitats. Lord Howe Island lies approximately 450km off the northern coast of New South Wales. It is a volcanic island with a fringing coral reef on its western shore, and a shallow (20 - 120 m) shelf surrounds the island. Bathymetry data are required in this area to help identify major seabed processes and habitats, especially relict reef structures, and to measure how well physical seabed properties act as surrogates of patterns of biodiversity on this mid-ocean carbonate shelf. The data are also required to enable modelling of tsunami as they interact with the shelf around the island and the coast. This report describes the methodology employed in creating detailed bathymetry data grids of the Lord Howe Island region. It covers data collection, quality control and gridding. Descriptions are provided of each dataset employed, the methods used to integrate the different datasets and the attributes of the new bathymetry models. Four new bathymetry grids are presented, including grids that integrate bathymetry with the island's topography.

<div>The Western Approaches to Torres Strait Bathymetry survey was acquired for the Australian Hydrographic Office (AHO) onboard the MV Pacific Conquest, an unmanned vehicle USV and VH-VEH Cessna 441 aircraft during the period 29 October 2020 – 21 February 2021.&nbsp;</div><div>This is a contracted survey conducted for the Australian Hydrographic Office by Fugro Australia Marine as part of the Hydroscheme Industry Partnership Program (HIPP). </div><div>The survey area is east of the Western approaches to the Torres Strait. </div><div>Bathymetry data was acquired using a Kongsberg EM2040 (Dual/Single Head and Dual swath), EM2040P and LADS HD+ and RIEGL VQ-820-G systems and processed using CARIS HIPS & SIPS 11.3.17, LADS HD+ GS, RiWorld processing software. </div><div>The dataset was then exported as a 30m resolution, 32 bit floating point GeoTIFF grid of the survey area.</div><div>This dataset is not to be used for navigational purposes.</div>

<div>The Varzin Passage to Merkara Shoal&nbsp;bathymetry survey was acquired for the Australian Hydrographic Office (AHO) during the period 4 Sep 2023 – 12 Apr 2024. This was a contracted survey conducted for the Australian Hydrographic Office by Fugro Australia as part of the Hydroscheme Industry Partnership Program. The survey area encompasses an area in Varzin Passage to Merkara Shoal. Bathymetry data was acquired using a LADS HD+, and processed using CARIS HIPS and SIPS, and QIMERA processing software. The dataset was then exported as a 30m resolution, 32 bit floating point GeoTIFF grid of the survey area.</div><div>This dataset is not to be used for navigational purposes.</div>