The pod of northern bottlenose whales, which can dive to depths of 2,000 metres and rarely visit coastal waters, were first noticed around Loch Goil but then ended up in the River Clyde.
Five of the whales - which can grow up to 11.2 meters in length and weigh over 7 tonnes - have been spotted around the Loch Long area and have entered some of the smaller lochs nearby ahead of a military exercise due shortly.
A spokeswoman for British Divers Marine Life Rescue said they have been concerned about the effect of underwater sound on the animals, which she said the whales are particularly sensitive to.
She said a team were trying "to herd the animals out using a number of boats in formation to get them back to open sea."
Europe's largest military exercise - Joint Warrior - begins on Saturday (October 3) with its headquarters at Faslane naval base next to Gare Loch.