As you swim your legs fall away as a tail grows between them. Your genitals are pushed forward and rest comfortably in a groove formed by your crotch as you turn over to view the changes. You now have a piscine tail with scales spreading from your thighs down into a large fanned tailfin. Your body has become more toned as you move forward with gentle strokes of your long powerful tail as you dive and give a dolphin leap. The mermaids giggle as you frolick in the water.