The Doctor dropped his hand to thread his fingers with Missy's, then giving her a poignant look, he walked her through the shallow part of the pool, and out. The loss of buoyancy from the water weighed their bodies down, but they easily adjusted as they walked over to the hut.
"Is there... anything else you want for your birthday?" he asked, feeling the need to fill the silence with speech. "You look... nice. In that..." he waved a finger at Missy's bathing suit. "All stringy and such." Of course, he didn't know what he was talking about, she could've still been wearing the old fashioned bathing suit, for all he knew.