Port Adelaide's river is famous for it bottle nose dolphin populations. With over 30 individuals in differing pods, you shouldn't have to look too hard to find a fin or two.
Port Adelaide has a wharf that juts out over the river, giving you the perfect free viewing area to search for these elusive locals.
If you were looking to go for the more upmarket option, then there are many boat cruise operators that can take you out for a day of adventure on the water, looking for the lovely dolphin families.
Be sure to check out the Port River Dolphin website to find out the most up to date information on which dolphins have been sighted, what interesting behaviour has been documented, and even if there are any new babies to look out for.