Red Bumps On Chest And Upper Shoulders. Some Have The

Red bumps on chest and upper shoulders. Some have the appearance of zits. Any ideas as to what it may be? My wife started getting them last week, she thought she may be allergic to something, but now I'm getting them too. I've had scabees before and I know this isn't it. I should say that we were on a cruise at the time of her initial reaction.