Final answer:
Sailors traditionally got a swallow tattoo after traveling over 5,000 nautical miles to symbolize experience and the hope of a safe return home.
Step-by-step explanation:
Traditionally, sailors would get a tattoo of a swallow after traveling over 5,000 nautical miles. This practice held significant meaning in the maritime community, symbolizing experience and prowess at sea. The swallow tattoo was also believed to ensure a safe return home, as swallows are known for their migratory behavior, often returning to the same location every year.