What is a flotilla?

A flotilla is a collection, grouping, or fleet of like and or differing flotation devices, usually in the form of transportation i.e. boats, ships, rafts, canoes etc. rather than emergency flotation devices such as life preservers or collected debris and wreckage.

Militarily speaking, a flotilla would be more of an armada consisting of many different types of armed warships and supporting transport craft. The D-Day invasion force that liberated Europe and brought an end to Nazi occupation during WWll certainly was transported and supported by a flotilla.
noun1.a group of small naval vessels, esp. a naval unit containingtwo or more squadrons.

2.a group moving together: The governor was followed by awhole flotilla of reporters.