Barwon Bluff in Portsea offers a diverse shore dive featuring a mix of reef, kelp forest, and wreck structures. Depths at this site range from 1 to 10 metres, with an average of 7 metres. Divers should be prepared for moderate currents, surf, and variable visibility between 5 and 15 metres. Due to the potential for shifting swell and surge, careful planning around slack tide is recommended. Entry requires a confident shore technique through the surf zone. Thermal protection is necessary as water temperatures range from 13C to 19C throughout the year. Parking is available, and guided tours are offered for those navigating the site.

Addiscot Beach is a shore dive on the Mornington Peninsula featuring a diverse mix of reef structures, kelp forests, and seagrass beds. Depths range from 1 to 10 metres with an average of 5 metres. The site is suited for intermediate divers capable of managing moderate currents and potential rip currents. Visibility varies significantly between 3 and 20 metres. Water temperatures remain cold year-round, ranging from 13C to 19C, necessitating appropriate thermal protection. Entry is via the shore and requires careful timing with wave sets. Divers should remain cautious of unstable sandstone cliffs and avoid the bases. Parking is available at the site.

The Rotomahana wreck is a deep, advanced dive located off Portsea, Australia. The site features a wreck structure and an adjacent wall at depths between 30 and 40 metres, with an average depth of 38 metres. Due to its proximity to Port Phillip Heads, the area experiences powerful tidal currents, making slack water the only safe time to dive. Visibility typically ranges from 10 to 30 metres. Given the depth and potential for strong currents, this site is strictly for experienced divers. A 7mm wetsuit with hood and gloves or a drysuit is recommended to manage water temperatures ranging from 13 to 18C.

The HMAS Canberra is a decommissioned warship resting upright on a sandy bottom near Portsea. The wreck offers a range of depths from 12 metres at the superstructure to 33 metres at the hull, requiring advanced buoyancy and gas management skills. Divers access the site by boat, and the wreck features multiple entry and exit points for penetration. Conditions vary, with moderate currents and surge common; the site is best dived during slack tide in calm weather. Visibility typically ranges between 6 and 15 metres. Due to water temperatures between 13C and 18C, a 7mm wetsuit or drysuit is recommended for the average 40-minute dive.

The HMAS J1 submarine is an artificial reef resting on the seabed at a depth of 35 to 36 metres. Located 4500 metres from shore near Port Phillip Heads, this wreck is a challenging dive suitable only for advanced divers. The site is subject to strong currents, requiring dives to be carefully timed for slack water. Visibility typically ranges from 10 to 20 metres. Due to the depth, cold water temperatures between 13C and 18C, and the risks associated with the overhead environment, this site demands careful decompression planning and appropriate thermal protection. Boat access is required, and guided tours are recommended for navigating this historic wreck.

The HMAS J4 is an upright submarine wreck resting at a depth of 26 to 27 metres off Portsea. This boat-access site is suited for advanced divers due to frequent strong currents and surge. The hull is heavily encrusted with kelp and seaweed. Visibility typically ranges between 5 and 15 metres. Due to the risk of entanglement and potential for silt-out, penetration is hazardous. Divers should plan their visit around slack water to manage the challenging conditions. Species recorded around this area include weedy seadragons, giant cuttlefish, western blue devils, and various wrasse species.

The HMAS J5 is a submarine wreck resting upright on the seabed at depths between 30 and 36 metres. This advanced dive requires boat access and is subject to moderate currents of 1 to 2 knots, which can funnel through the structure. Visibility typically ranges from 5 to 10 metres. The wreck features an overhead environment with tight internal spaces, making penetration hazardous due to potential silt-out and structural deterioration. Divers should be prepared for water temperatures between 13C and 18C. Given the depth and conditions, redundant air sources and multiple lights are mandatory for those planning to explore the interior of the hull.

The SS Coogee is a wreck dive situated in the treacherous entrance to Port Phillip Bay known as The Rip. Resting at depths between 29 and 35 metres, this site is strictly for advanced divers due to extreme tidal currents that can exceed 6 knots. Diving must be conducted exclusively during slack water to ensure safety. Visibility ranges from 4 to 25 metres, with the best conditions typically occurring during the winter months. Access is by boat only, located 4 kilometres from shore. Given the depth and the potential for strong currents, divers should plan for decompression and use a local charter operator familiar with the specific tidal windows.