Deer Island (Isla de Venados) is visible from just about anywhere in Mazatlan. It's the larges of the three islands off of the shores of the Golden Zone and has a lot to offer for a half-day trip. After a 5-minute motor boat ride or a 20-minute paddle on a kayak you will find yourself swimming in Caribbean like clear blue water with a unique perspective of the city. There are no services on the island so load up if you go on your own or take one of many tours that include lunch and drinks. It is also not uncommon for locals and visitors to camp overnight on the island. Cell service from the mainland is within range with a strong signal for your peace of mind.