Me and my big mouth! >.<! Chase,I'm so going to get this guess wrong...Punta del Este in Uruguay.
The thing with deduction exercises, is to create your own clues and only guess the exact answer when you're at least 80% sure. Do not guess if you are unsure.
The idea is to ask as many questions as possible to pinpoint this location. First you might ask:
About its physical property -- Is it longer than 10 miles? (Yes)
Then narrow down locations -- Is it in South America? (Yes) Is it in the Southern Hemisphere? (Yes) Is it on the Pacific coast? (No, meaning it's facing the Atlantic)
It could take you about 4-6 questions to build your clue.
From these questions you'll have a list of countries: Brazil, Uruguay, or Argentina.
Instead of guessing beach names directly (and wasting questions), you would want to narrow it down further by asking if it's in one of these nations. (You might spend up to 2 questions here to get the correct country. This usually leaves you with 3-5 questions left to guess the beach names.)
Once you know the country it is in, only
then you may start guessing which beach.
These games are designed so that you should be able to ask/guess correctly within 11 questions. You just need to learn how to build your clues.
That said...
The answer is
Mar del Plata or
San Clemente del Tuyú, in the province of Buenos Aires, Argentina. I would have accepted either answer because the beach stretches across both areas and is Argentina's longest beachfront. Something you easily could have guessed if you established the country first.