Port Underwood, New Zealand offers 2 beaches perfect for sunbathing, surfing, swimming, and more. Port Underwood, Marlborough, New Zealand, is known for its scenic coastal landscapes and historical significance as the site of early European settlement and whaling activities. The best time to travel to Port Underwood, New Zealand, is during the summer months of December to February, when the average air temperature is around 20°C (68°F) and the water temperature is approximately 17°C (63°F). Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!