<div id="container">
  <div id="water"></div>
</div>
<svg xlmns="http://www.w3.org/2000/svg" version="1.1">
  <filter id="turbulence" filterUnits="objectBoundingBox" x="0" y="0" width="100%" height="100%">
    <feTurbulence id="feturbulence" type="fractalNoise" numOctaves="3" seed="2"></feTurbulence>
    <feDisplacementMap xChannelSelector="G" yChannelSelector="B" scale="20" in="SourceGraphic"></feDisplacementMap>
  </filter>
</svg>
<a id="codepen-link" href="https://www.codepen.io/seanfree" target="_blank"></a>

$lakeImg: 'https://s3-us-west-2.amazonaws.com/s.cdpn.io/544318/lake.jpg';

body {
  background: #cfcfcf;
}
#container, #water {
  background-image: url($lakeImg);
  background-position: center bottom;
}
  
#container {
  position: absolute;
  top: calc(50% - 206px);
  left: calc(50% - 275px);
  height: 412px;
  width: 550px;
  
  &:after {
    position: absolute;
    top: 10%;
    left: 2.5%;
    z-index: -1;
    content: '';
    display: block;
    height: 95%;
    width: 95%;
    background: #0f0f0f;
    filter: blur(30px);
  }
  
  #water {
    position: absolute;
    bottom: 0;
    width: 100%;
    height: 66%;
    filter: url('#turbulence');
    overflow: hidden;
  }
}
#codepen-link {
  position: absolute;
  bottom: 30px;
  right: 30px;
  height: 40px;
  width: 40px;
  z-index: 10;
  border-radius: 50%;
  box-sizing: border-box;
  background-image: url('https://s3-us-west-2.amazonaws.com/s.cdpn.io/544318/logo.jpg');
  background-position: center center;
  background-size: cover;
  opacity: 0.5;
  transition: all 0.25s;
  &:hover {
    opacity: 0.8;
    box-shadow: 0 0 6px #0c0c0c;
  }
}

let timeline = new TimelineMax({
    repeat: -1,
    yoyo: true
  }),
  feTurb = document.querySelector('#feturbulence');

timeline.add(
  TweenMax.to(feTurb, 15, {
    onUpdate: function() {
      let bfX = this.progress() * 0.005 + 0.015, //base frequency x
        bfY = this.progress() * 0.05 + 0.1; //base frequency y
      feTurb.setAttribute('baseFrequency', `${bfX} ${bfY}`);
    }
  }), 0
);