Some call it waddling

But read this description from Midsummer Night's Dream

His mother was a votaress of my order:
And, in the spiced Indian air, by night,
Full often hath she gossip'd by my side,
And sat with me on Neptune's yellow sands,
Marking the embarked traders on the flood.
When we have laugh'd to see the sails conceive
And grow big-bellied with the wanton wind;
Which she, with pretty and with swimming gait
Following,--her womb then rich with my young squire,
Would imitate, and sail upon the land,
To fetch me trifles, and return again,
As from a voyage, rich with merchandise.

"pretty and swimming gait" is a much nicer way of describing it, I think.