<p class="ingestion featured-caption">This salt flat in Bolivia is perfect for creating optical illusions.iFerol/Shutterstock</p><ul class="summary-list"><li>Across the world, there are naturally occurring optical illusions that captivate spectators. </li><li>Cloud formations can sometimes make it seem like there's an ocean or a UFO in the sky.</li></ul><p>Everyone loves an optical illusion — even if they leave us completely <a href="https://www.businessinsider.com/best-optical-illusions-photos-2017-10" target="_blank" rel="noopener">stumped</a> — and they're all around us in the natural world.</p><p>From an underwater waterfall in the Indian Ocean to a surrealist scene in Namibia, we rounded up 18 naturally occurring illusions and optical phenomena that will make you double-take. </p><p>If you can't fathom how these places are real, there's good news: Some of the locations named on this list are accessible to visitors, so if you're looking for <a href="https://www.businessinsider.com/top-summer-trip-destinations-travel-spots-countries-google-flights-2024-4" rel>travel inspiration</a>, you can investigate them yourself.</p><p>Take a closer look below and find out how these illusions are created.</p><p><em>Lucy Yang contributed to an earlier version of this report.</em></p>