According to one legend, a sailor tattooed with one swallow had travelled over 5,000 nautical miles, a sailor with two swallows had travelled 10,000 nautical miles. Travelling these great distances was extremely difficult and dangerous in the early days of sailing, so one or more swallow tattoos denoted a very experienced and valuable sailor.
Legend holds that since swallows return to the same location every year to mate and nest, it was believed the swallows would guarantee the sailor returns home safely. A sailor would have one swallow tattooed before setting out on a journey, and the second swallow tattooed at the end of their tour of duty, upon return to their home port. It is also said that if the sailor drowns, the swallows will carry his soul to heaven