"What are we going to do?" asked Jess.
"I don't know. But we need to go somewhere nobody is going to find us until we can figure out what to do. And I know a deserted island that would be a good place for that."
"Lead the way. We better get that statue too; I lost it when that wave hit us..."
You pull yourself into the water until its deep enough to start using your tail. Jess is right behind you, but maneuvering awkwardly since unlike you she hasn't spent half the day with a tail. You both search for the statue but can't find it. After awhile, you give up in frustration and head off to the island together. Perhaps you will have better luck searching for it in the morning?
The sun has gone down, but despite the darkness you are able to find the island again. You and Jess pull your mer-bodies up on the beach and lay there on your backs worn out from the swim.
After a few minutes, you roll over to Jess. Despite the bizarre gender reversal of you becoming a mermaid and her becoming a merman, she still looks beautiful to you.
"If we're going to have to figure a way out of this, I'm glad we're doing so together" you say.
She smiles and leans into a kiss. It's a long one and it leads to several more. You start to roll on top of her, but she reverses it and rolls on to of you. "I get to be on top this time" Jess explains.
You don't complain as you make out and grind your tails together, as Jess caresses your breasts. You're incredibly aroused but then you remember your self-exploration earlier that day and your apparent lack of of vagina and you didn't see any male equipment on merman-Jess. But then you feel something poke you in your tail and you have a good idea what it is. A moment later she inside of you. You guess merfolk genitalia must be hidden when not in use.
As your love making continues you realize your skin is starting to feel dry. You feel your tail slowly split and reform into legs. You feel Jess withdrawl from you as she transforms from a merman back into a woman. But as your legs continue and you feel your penis return, the sex is reversed as you enter Jess who has a vagina again.
Things continue until you both collapse on the beach exhausted. It was the strangest and most intense sex of your life.