"Look at you, being one with the sea. A beautiful mermaid indeed." If it's relaxation she wants, he can help. He kisses her cheek before saying-- "Please trust me."

Then he moves to be next to her instead of in front, and gently moves his arms under her legs to bring them up. Midge will feel a lack of balance for a second, but soon Jaskier has her floating on the water, always keeping a hand on her arm and leg to keep her from slipping away.