One of the best places to swim in the Noosa River is from the Noosa Spit Recreation Reserve. Many travellers seem to miss this peaceful spot at the mouth of the Noosa River. It's a great place to escape the crowds at main beach while still enjoying the best of what Noosa has to offer. There is plenty of parking (which can still fill up quickly during peak summer holidays) and various access points to the river which has calm, tropical blue waters and soft, sandy coves. During high tide, the water will be crystal clear and as the tide goes out, there will be a bunch of sandbanks you can walk out onto and explore.
My favourite part is the off-leash dog beach, where my little pup loves playing in the calm water. This area is ideal for a lazy afternoon with your furry friend. If you keep driving further along Claude Batten Drive, you'll come across a few prime parking spots right by the river. You'll have to get in quick as these spots are usually taken by vans given that it's in such a great location with an unbeatable view. From here you can also walk to the small break wall at the beach for a view looking back over the busy main beach and the river mouth.