Before the bridge was built, the only way people could get to Anglesey island was by a ferry from Holyhead. The water of the Menai Strait is very rough and dangerous, so it was hard for people to use their own boats or swim to the island. The people who lived on Anglesey sold cattle that they raised. The cattle were forced to swim through the dangerous water, with many of them often dying. If the cows survived the trip, they were sent to London and other places to be sold. 