Gates said the USS Peleliu is now off the coast near Karachi, carrying 19 helicopters and a complement of about 1,000 Marines.
The six U.S. helicopters which were sent to Pakistan from Afghanistan earlier have been helping rescue people and deliver aid supplies. Gates said the Peleliu's complement will replace six combat helicopters on loan from the U.S. war effort in Afghanistan.
Gates said President Barack Obama has directed his administration to "lean forward" in offering help to the Pakistanis, which he stressed will be at a pace dictated by Pakistan's needs and its ability to handle aid.
"There's no point in having a lot of helicopters if we don't have the relief supplies to deliver," Gates told reporters traveling with him to Florida. He said the State Department, the U.S. Agency for International Development and other areas of the government will have to be involved in helping Pakistan recover.
Gates and other U.S. officials say the Pakistani military has had to divert some troops and attention from fighting insurgents to help in flood relief. The U.S. is trying to lighten that load, but Gates said the overall impact of the shift ultimately will depend on how many troops are diverted.
"We weren't expecting them to undertake new offensives for some period of time anyway," Gates said of the Pakistani military's efforts against insurgents along its border with Afghanistan. He also addressed reports that extremist groups are helping in relief efforts, allowing them to appear to some parts of the population as a positive force.
"It does offer them an opportunity," Gates said.
Gates the U.S. in turn is pleased to offer Islamabad a way of showing the Pakistani population that its government and military and military are able and ready to care for their own people.
On Tuesday, the Pakistani Taliban said the flooding was God's punishment to Pakistanis for accepting secular leaders and urged Pakistanis to boycott foreign aid.