Today we visited Tydeman Reef, which is part of a group of reefs that are unusual on the Great Barrier Reef due to their geographical orientation. Usually reefs on the Great Barrier Reef are orientated north to south across about 2,300 kilometres. In contrast, the reefs here are oriented almost east to west, and therefore are exposed to different hydrodynamic regimes (i.e. tidal currents, wave energy). As a consequence, we observed very distinctive coral reef arrangements. Sheltered areas were entirely covered by massive and round corals. As we continued the survey across the reef we encountered a mixed composition of branching and massive reef builders, as well as large extensions of plating corals. These reef assemblages host a large variety of fish species due to the structure provided by the corals. Also, we came across dramatic changes in 'reefscape', from step to walls, to gentle slopes, to prominent spoors and grooves and flat terraces. This is a clear example of the diversity of ecosystems we can find across the seascape, which looks contrastingly homogeneous from the surface. Imagine how much diversity there is in the almost 350,000 square kilometres covered by the Great Barrier Reef.