JSFiddle - React, Tailwind, and code Playground

HTML

<svg id="map" version="1.1" viewBox="0 0 300 300">
    <image width="300" height="300" xlink:href="http://placehold.it/300"/>
    
    <a xlink:href="#t_1">
        <rect x="50" y="50" width="50" height="50" />
    </a>
    
    <a xlink:href="#t_2">
        <rect x="150" y="150" width="50" height="50" />
    </a>
</svg>

<div class="t" id="t_1">Tooltip 1</div>
<div class="t" id="t_2">Tooltip 2</div>

CSS

html, body {
    width: 100%;
    margin: 0;
    padding: 0;
}

svg {
    display: block;
    width: 80%;
    max-width: 300px;
    margin: 0 auto;
}

svg rect {
    fill: white;
    opacity: 0.1;
    transition: all 0.2s linear;
}

svg rect:hover {
    opacity: 0.8;
}

.t {
    opacity: 0;
    position: absolute;
    left: 0;
    top: 0;
    transition: opacity 0.4s linear;
}

.t.active {
    opacity: 1;
}

JavaScript

var map = document.getElementById('map');
var areas = map.getElementsByTagName('a');
var offset = { left: 30, top: 70 };

for (var i = 0; i < areas.length; i++) {
    areas[i].onmouseover = function() {
        // get child element
        var c = this.firstElementChild;
        // get tooltip
        var t = document.getElementById(this.getAttribute('xlink:href').substr(1));
        // set styles
        t.style.left = (map.offsetLeft + parseInt(c.getAttribute('x')) + offset.left) + 'px';
        t.style.top = (map.offsetTop + parseInt(c.getAttribute('y')) + offset.top) + 'px';
        // show it
        t.classList.toggle('active');
    }
    areas[i].onmouseout = function() {
        // get tooltip
        var t = document.getElementById(this.getAttribute('xlink:href').substr(1));
        // hide it
        t.classList.toggle('active');
    }
}