A winning selection found on “EP,” the debut release by Underwater Seacreatures, “Speak Up” drips with sensuality. With its echo-y panoply of bubbling bass, overmodulated vocals and treated synthesizers, the song boasts a tangible urgency. The Seacreatures, Nathan Keeys and Marcos de Silva originally came together to play hip-hop but found themselves charting fresher waterways. “From the beginning, we took at D.I.Y. approach and started building on it,” de Silva says. While they only played their first gig, a house party, earlier this month, Underwater Seacreatures has had national music blogs in a tizzy over their dreamy studio concoctions, which explore a keyboard-driven music genre known as chill wave (“it’s beneath the Richmond underground right now,” Keeys says). The duo will continue their subsonic voyages on a soon-to-drop sophomore effort, “Women.” underwaterseacreatures.bandcamp.com.