While Mljet is a beautiful destination year-round, the best time to visit is during the shoulder seasons of May, June, September, and early October.During these months, the weather is pleasantly warm and sunny, ideal for swimming, hiking, and cycling, without the intense heat of mid-summer. You'll find the Mljet National Park, including the Big and Small Lakes, less crowded, allowing for a more serene experience exploring the Benedictine monastery on St. Mary's Islet or enjoying the walking trails. Water temperatures are also comfortable for swimming and snorkeling.For travelers looking for a quieter experience, May and early June offer lush greenery and blooming wildflowers, while September and early October boast warm sea temperatures and a more relaxed pace as the peak tourist season winds down.