Agreed with others mentioning buddy's that don't stick to the plan or wander off. Additionally though are buddies that think they can go to depths they are not certified for, it is always good to verify when making the dive plan what their cert level really is. Ask them how many dives they have been on, it will usually be an indicator to what you might expect. Of course the best is when you can have a buddy you can trust and consistently dive with, like a husband or wife!
