Have some unbeta's fluff!
In the past, Dean had thought a lot about taking Cas to the beach, not that he'd ever told anyone that he'd had these thoughts.
Whenever he did have them, they included things like the two of them swimming together, spending all day on the beach until they can watch the sun set into the sea. They included giant soft pretzels and sea salt ice cream and margaritas at a bar at night. In some of the more explicit daydreams, they'd fall into each other, fresh from the water, pawing, rutting, and kissing, the taste of the ocean on every inch of skin because the want was too strong to waste time doing anything else.
So the circumstances when they actually get to go to the beach are less than ideal. As a demon, Dean can't get in the water with Cas. He can only watch the snorkeling fallen angel who is enraptured by the scant wildlife near the shore and hope the guy doesn't drown because there isn't a whole lot Dean can do to help if he does.
There can't be any pretzels or sea salt ice cream or margaritas because as a demon, Dean has the worst fucking food allergy in the world.
They can't sit on the beach all day because even just the bite of the salty sea air is enough to set Dean's skin to tingling in much the same way sun burns does to an almost human Cas.
And there is no desperately falling into each other fresh from the sea. There isn't even any touching fresh from the sea. When they get back to the condo, Castiel has to shower thoroughly, and even then there's still a slight sizzle when they touch.
So it may be less than ideal, but Dean wouldn't trade it for the world.
Because maybe he can't actually swim with Cas, but he still gets to watch the joy on the fallen angel's face at every small discovery he makes, gets to admire the pull of muscle and the way the water runs down Cas's back in a way he couldn't if he were up there in the action.
Because while maybe Dean can't have the pretzels and ice cream and salt-ringed margaritas, Cas still can. And now he can actually taste and appreciate the flavors on his tongue. Nothing tastes like molecules anymore.
Because though they may not be able to watch the sunset on the beach, they can instead they watch it from their condo, curled up into each other and sneaking kisses and touches in ways they'd never be able to down on the sand where people still linger.
And because when Cas emerges from the shower, the fresh smell of soap and sea breeze mingles on his skin in the best way, reminiscent of the scent he'd still carried when he'd had his grace. And while the burn under Dean's lips and fingers from residual salt stings him as he worships against the skin of a fallen angel, it only spurs him on- a reminder that this is what it once felt like, when grace would sizzle under skin, back before they were broken. It's a reminder that broken or not, they are still alive, and they still have each other.
So it may not be ideal, but maybe it's just a little bit better.