Live music, food , shops. Best if you go around 6.
Mazatlán's malecón is considered one of the longest in the world, has a length of about 21 km (roughly 13 miles), along the Pacific coast, among which you can find high cliffs, monuments, gazebos, shops, art exhibits. Walk as far as you can then take a pulmonia to olas altas (the end).
The hike to the lighthouse takes about 30-45 minutes, depending on how fast you hike, and is about 1.5 miles long. The trek is pretty steep, so even though it's not long it gives you a good workout.
The end of the male con where you can find divers, snacks, sea food and a Beatles exhibit.