"The" in your question is missing a word to make it complete. What are you trying to find out about the Marlborough Sounds? For example:
* What is the *history* of the Marlborough Sounds?
* What is the *best time of year to visit* the Marlborough Sounds?
* What are the *most popular activities* in the Marlborough Sounds?
Once you provide more information, I can help you find the answer.