Dolphins 
To dream about a dolphin suggests teaching, wisdom, and the faith you have in others. By trusting your mind to perform, you will achieve the things you want in life. This dream can also indicate the conveyance that is being built between your conscious and subconscious mind. Dolphins are symbolic of your ability to work through your feelings.
To dream that you are on a dolphin suggests that you have faith in the future and caring for others.
Killer Whale
A killer whale in a dream represents spiritual guidance. The killer whale is a dangerous animal which in a dream represents a part of your psyche which has great power but which must be followed carefully.
Hammerhead shark
Dreaming of a hammerhead shark denotes your fear of an enemy or danger. While fish and dolphins are beneficial and positive images to see in a dream, sharks in general represent all things greedy and cold. Regularly dreaming of a hammerhead shark means that there is someone in your life who may be deceiving you in some way. They are not being completely honest with you.
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