Game of Thrones! How do the White Walkers Get Past the Wall⁉

In the season opener last week, the Hound saw the "dead marching past" where the "Wall met the Sea."

This had the Internet chattering. If they could just march past, why did they wait so long? Internet sleuths have discovered the answer in the title sequence.

Possible Spoilers ahead

See the picture above from the sequence.

In previous seasons, the wall went from sea to sea. But now... the sea has ❄️frozen❄️ over‼

So now they can just walk past😱

UCJ, UNILORIN.