If you have a dream about a deep river it means that you have a lot of way to go before you get to your destination in life and that you won't be able to stop for breaks. Once you start your journey, you must continue with it and if you try to take a detour you will fail and have to start over again from ground zero. However once you reach the end, your reward will be that much more important and effective to you. This is a great thing for you and should help to motivate you even more than you could ever imagine.
Dreaming of a deep sea means that you feel like your life is full of possibilities. No matter which way you go, left, right, down, up, east, west, north, south, anywhere, you are going to eventually get somewhere new in your life and you will see and experience new things. This is a fantastic thing to know about yourself because it keep you prepared for the best things in your life and lets you remember that the best is still yet to come.
Depth is a serious concern to a lot of humans, whether it is depth of a river, depth of emotion, or depth of expression, there are a lot of different modes of human expression and ways that humans can express themselves. Thus, because of the many levels of depth that humans themselves possess it is not hard to imagine why a person might dream of endless levels of depth that are available to be seen by many different cultures and creeds. If you have a dream in which you see a deep well it means that you are concerned with that very endless depth that was just referenced, you are being self reflective about it and thinking about just how crazy it is that you are able to conceive of all of this.