A tide is the alternate rise and fall of sea level. It happens twice in each lunar day and is caused by the gravitational pull of the sun and moon. A tide could be high or low. However, to swim against the tide means to do something contrary or to disagree with a general opinion on an issue. It means doing things in the opposite direction of what the majority is doing.
Sometimes it is good to swim against the tide, other times it may not be such a great idea. Although doing something that is contrary to popular belief can sometimes make you unique, original and innovative, however, it could also turn out bad when you are not sure of what you are doing.
It will be wise for one to be pretty sure of what they are doing anytime they decide to go against the general way of doing things.
Kelly Smith