The first couple of nights were not so bad (there was a cockroach outside my bathroom door the first morning, but I had mentally prepared myself for that and scooted it outside my hotel door with my shoe). From then on, I kept the bathroom light on, remembering that the cockroaches don't like light. I also kept my shower door closed, since I had heard that they climb up through drains. But on the third night, a large group of about 20 eighteen to twenty year olds arrived at the hotel. They were OK during the day - yes, they dominated the deep end of the hotel pool, but they usually stayed at the pool for only two hours or so. The bigger problem was at night. They slammed doors, screamed out loud (and I mean actual screams) and even shot off firecrackers on two different nights. OK, I was young once also - I can tolerate the noise until even let's say 1am. But 3:30 am is not OK for other hotel guests. Seems the problem is, hotel management doesn't really care, and actually told me as much. Youngsters will be youngsters was the overriding message. I had to just tolerate it for 4 nights until the "youngsters" left. Management does not give any indication that they have a problem with this kind of behavior. Also, the noise from the street in Mazatlan is overwhelming. Roadsters revving engines all night long, sirens going off, and constant traffic all night long. The street is immediately outside of the hotels. It is a dirty, dilapidated city that has fallen to ruins in the poor economy. Not a nice place to visit at all. Do not stay at the Costa de Oro if you cannot change your destination plans. Visit other hotels along the same strip of road and find another (perhaps Inn at Mazatlan?). But I would find another destination in Mexico altogether.