Glenelg Beach is Adelaide's most popular and busiest beach. It is often lively, even during the off-season. However, it is hardly ever too crowded. There are several activities available, even if you don't feel like going in to the sea for a swim or hanging out by the shore.
Apart from the beautiful beach, there are several places to see including the shark museum and the heritage town hall. The marina is also a great place to hang out and eat. You can even book yourself a boat ride and dolphin watching session.
From the city, one good way to reach Glenelg is by taking the tram at Victoria Square.
I always enjoy visiting Glenelg, for its liveliness and fun atmosphere.