Most imagine manta ray tattoos as well as other aquatic artwork as being simply a personal preference. People like sea creatures, so they allow them to be tattooed on their skin, essentially.
Though this may be the case for some, both ancient and contemporary cultures view sea life as representing everything that the human spirit possesses.
The manta ray directly depicts cultural beliefs, especially Polynesian.
Polynesians believe that the manta ray symbolizes spirituality and their guardians. Believed to patrol the waters in a way that protects those on Earth, manta rays are a sign of power and ancient wisdom. Modern day Hawaiians believe that these creatures leap out of the water in order to fill the air with their experience in the sea and pass on knowledge that those above do not know yet. For others, manta rays create a connection to human emotions in a very profound manner.
These animals are known to move slowly and gracefully. Because of these mannerisms, people correlate the animal with emotional turmoil and the manner that humans are able to move through difficult times. Essentially, the strength of these animals allows them to move through troubled water, so those above can do the same.