Take a boat from Tarkarli/Devbagh to Sindhudurg Fort (boats typically operate 9AM–3PM); explore the island fort built by Shivaji — great history and sea views.
Jaigad Fort sits on a cliff with sweeping views of the Arabian Sea and the Jaigad creek; the site is best visited in the morning and is open in daylight hours.
Visit the popular Ganapatipule Swayambhu Ganpati temple and relax on the adjoining clean beach; temple is open morning to evening and is a cultural highlight.