These chemicals speed up your heart-rate, shut down your immune system, digestion, and reproductive systems, allowing you to use all the energy that would usually go toward, say, digesting a granola bar for swimming like hell to the beach.

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"As a for-profit business that's an attractive pond to go swimming in, " says Mr Beck.

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There are a few spots for snorkelling and swimming, but the farther off shore you go, the closer to surfing territory you get.

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