President Barack Obama eats Shave Ice with family and friends at Island Snow at Kailua Beach Center while on vacation with the first family in Kailua, Hawaii, Monday, Dec. 27, 2010.

*President Barack Obama and his family visited a famed nature sanctuary in Hawaii on Tuesday, dipping into the water for some snorkeling and steering clear of reporters, reports the AP.

The Hanauma Bay Nature Preserve, known for its clear water and rich marine life, is one of the world’s best known — and busiest — snorkeling spots.

Obama, his wife Michelle, daughters Malia and Sasha, and a group of friends and their children arrived at the site late in the morning and stayed for two hours.

Hanauma, run by the city and county of Honolulu, is normally closed for maintenance on Tuesday but opened for two hours exclusively for the president and his party.

Reporters accompanying Obama were under explicit instructions to refrain from taking pictures.

Martha McDaniel, the assistant park manager, said officials have been making aggressive efforts to limit the number of visitors to keep the reef from getting trampled.

In the 1990s more than three million visitors visited the park each year, a number that dropped to around 800,000 in 2010.

Visitors must watch a 15-minute video on safety and coral preservation. The Obamas saw the video last year while on vacation, and it was unclear if they saw it again on Tuesday.

On Monday Obama spent the day with his children and friends bowling and playing basketball before treating them to Hawaii’s famed shave ice at a store near his rental home in Kailua, in northeastern Oahu Island. [See photos below.]

The first family is spending a quiet, 10-day vacation in Hawaii, where Obama was born 49 years ago. He is scheduled to remain in Hawaii until Sunday.

President Barack Obama, right, turns to take shave Ice orders from family and friends as his daughter Sasha Obama, left, stands at the counter at Island Snow at Kailua Beach Center while on vacation with the first family in Kailua, Hawaii, Monday, Dec. 27, 2010.

Obama jokes around with store employee Renee Ebia (L).

Obama and his daughter Malia (2nd L) eat "shave ice" with family friends outside of Island Snow.

Obama waves from the first fairway at Mid-Pacific County club with friend Mike Ramos during his holiday vacation in Kaneohe, Hawaii, Tuesday, Dec. 28, 2010.