A source reported that Gates and his group arrived at the site at 5 pm on Wednesday and spent over an hour enjoying tea and watching the sunset with a local tea artisan.
The source added that the Son Tra Peninsula's management board limited visitor numbers to the site, noting that Gates' bodyguards stood guard at the mountain's base.
Located seven kilometres from Danang city centre, Ban Co Mountain, rising 700 metres above sea level, marks the highest point on the Son Tra Peninsula. It is a favoured tourist spot in the city, offering panoramic views of the city and beaches.
Gates and his partner are exploring Danang and Hoi An following their attendance at a pre-wedding party for Asia's wealthiest billionaire Mukesh Ambani's son in India.
The couple arrived on March 4 at Danang International Airport in their private plane and stayed at a five-star resort in Son Tra District.
Gates is visiting Vietnam for approximately five days, 18 years after his first visit to the country.
