"Sienna" is a song by American indie pop band the MarÃÂas, released on May 31, 2024 from their second studio album Submarine (2024).
The song imagines the life of a child named Sienna that MarÃÂa Zardoya and Josh Conway might have had if they had not ended their relationship. Zardoya pictures that she would have been cute and looked like Conway. Sienna is described as manifesting the characteristics of her parents and engaging in the same things they do, such as running around, jumping in the pool and singing to her pets. Zardoya eventually comes to terms with the fact that she will never exist.
Cerys Davies of Los Angeles Times wrote that the song was "dreamy yet heart-wrenching". Hannah Burns and Marc Maleri of Atwood Magazine both lauded the song. Burns regarded it as having some of the best lines from Submarine, mentioning "I live under your eyelids / I'll always be yours" and the outro ("On the beach in the winter / When the waves were mad / Down by the water, crystal clear / See her face in the forest then it disappears"), while Maleri described the lyrics as "hauntingly gorgeous".