Carnival Cruise Lines has reported increased net income for the third quarter of 1988 compared to the same period last year, while carrying virtually the same number of passengers.

Reported net income is $56.3 million, on revenues of $157.6 million, for the third quarter ended August 31, 1988. That is a 12 percent increase in net income, up from $50 million, for the same quarter last year, while cruise revenues only increased by two percent.

Carnival reported an average occupancy level of 120.7 percent. 161,720 passengers sailed aboard Carnival ships during the third quarter, compared to 161,761 last year. According to Carnival, less than one-half of one percent traveled for free or at reduced rates.

For the first nine months of the year, Carnival has reported net income of $154.3 million, up 30 percent from $118.3 million for the same period last year. Revenues are up seven percent, from $438.2 million to $469.3 million. The line carried 448,161 passengers for an occupancy level of 113.5 percent.

In other news, Carnival has announced that it has signed a letter of intent with the Hotel Corporation of the Bahamas, a Bahamian government entity, to purchase the Cable Beach Hotel in Nassau for approximately $82.5 million.

The 700-room property is adjacent to Carnival's Crystal palace Resort & Casino, which is under construction, but when in full operation in late 1989, will give Carnival a total of 1,587 rooms.