She shot him a smile as she looked at the igloo entrance. There was no spell, no magic wand, nothing at all out of the ordinary as she stood there, unless you thought of tugging at your gloves and adjusting one's coat as particularly unusual.
It wasn't that Mary Poppins was so immensely magical or powerful or strong. She just had a certain way about her that the world wanted to bend for her.
"I'm going to go in," she said and then dropped to her knees in the snow. "It's not very far, just a few steps."
With as much grace as one can muster when crawling on one's hands and knees through, Mary slipped through the entrance and went into the igloo.