O'Sullivan Beach Boat Ramp is a popular launch facility in Adelaide's southern suburbs, situated near Christies Beach with direct access to Gulf St Vincent.

Managed by the City of Onkaparinga, the ramp serves both recreational boaters and anglers heading out onto the gulf's coastal waters. The facility features two concrete lanes and has undergone upgrades to improve access and safety.

Nearby amenities include toilets, fish cleaning areas, and parking. A launch permit is required; casual users can purchase a ramp-use ticket from the on-site Harbour Kiosk, which also stocks bait, tackle, and food.

Periodic permits are available online through the City of Onkaparinga. Boaters are advised to time their launch around mid to high tide, as low-tide conditions can expose shallow areas and make launching more difficult.

Sand buildup near the ramp can also be a factor to watch.