In the case of the USNS Vandenberg, you sink it, reports CBS News correspondent Kelly Cobiella.
In its heyday in the 1960s, the Vandenberg watched space launches, and spied on Russia.
"It helped with the Cold War - it fought as hard as anyone," said veteran Mac Monroe.
Before long it'll be an artificial reef, an underwater playground for divers and fish.
"This is the best wreck dive in the world you can drive to," said dive boat captain Joe Weatherby. "That's a fact."
Artificial reefs are a growth industry - you can swim through old subway cars off the coast of South Carolina, and snorkel up to a concrete margarita bar near Miami Beach. But they don't always work out as planned. Tires dumped off the coast of Ft. Lauderdale to attract fish created a dead zone. The Navy is still removing them.
"We think it is going to be a home run for the environment, and for our economy," said Weatherby. "This is good business. And at the same time we're taking pressure of our natural reef - giving it a break."
It cost more than $8 million to clean and sink the Vandenberg. Locals both above and below water are hoping it pays.