Tabacón Thermal Resort & Spa is the perfect place for couples to get steamy while soaking in natural hot springs. The resort's spread across 900 acres of lush rainforest reserve near the base of Costa Rica's Arenal Volcano, with thermal springs and cascading waterfalls naturally heated by the volcano's magma and outdoor spa bungalows where treatments are rendered the sounds of rushing streams and local wildlife. To really turn up the heat, opt for a treatment that includes a soak in a private jacuzzi filled with natural spring water, curl up in a cabana with cocktails at the adults-only Shangri-La Gardens, or rinse off together after the springs in your room's see-through rainforest shower.