The Light the South Art Trail, a collection of 40 uniquely designed lighthouses including five on the Isle of Wight, concludes on September 1.
Having started on July 1, the event supports Southampton Hospitals Charity.
Each lighthouse has a code, which participants can log into a free app to track their progress. There are five in Cowes and 35 in Southampton.
Red Funnel is encouraging participation by offering reduced ferry fees for those who locate their sponsored lighthouses.
The lighthouses will then be auctioned on September 20 at the end of the Southampton International Boat Show.
Additionally, there is a 'Window Spotting' trail featuring mini lighthouse replicas till September 12.
Fran Collins, CEO, Red Funnel said: “The trail is a lot of fun and a great way to spend time with friends and family while also getting some exercise and enjoying the sunshine.
"Several of our Red Funnel colleagues have already completed the trail with their friends, colleagues or family - indeed, one of our colleagues and her children recently logged 22,000 steps finding all the lighthouses in just one day, proving that the Light the South trail can be completed as a one-day challenge."
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