Everyone knows … nothing attracts hot, young naked women like a badass grotto (just ask Hugh Hefner) which might be why Elin Nordegren is officially SCRAPPING plans to build one at her post-Tiger Florida mansion.

TMZ has learned … Elin’s engineer has filed documents to alter the specs on her multi-million dollar mansion re-building project in North Palm Beach.

In the docs, the engineer notes that Elin has decided to 86 the pool grotto and make a “slight reconfiguration” in the shape of the pool.

As we previously reported, Elin bought the place for a cool $12.5 mil … then leveled it to build her dream home from the ground up. Clearly, money is not an issue.

For the record, Hugh Hefner has several mattresses surrounding his grotto … for naps.