Nothing beats relaxing by the water while you're on vacation. Take a picnic to Lago de las Tortugas and then hang around for a pretty sunset.
When you've finished up at this Marbella body of water, why not check out Puerto Banús Beach, Puerto Banús Marina, and El Corte Ingles Shopping Center? They're not too far from Lago de las Tortugas and also a hit with many tourists.