Searches started at 4 pm from the Daisy field area of the line (beside Coshowen on the foyle road when the tide is out.
Searches have also been carried out over the border at Carrigans in Donegal near the River Foyle for any trace of Martin.
A friend posted on Facebook: “We have to keep searching and get Marty home to his family.. We are all worried sick and just want him back.
“Rememeber if anyone has any info at all or think they might have seen Marty please please get it touch with myself via pm or the police on 101 with the reference number 25 (10/08)
“Please Share – Search at 4pm If anyone has a spare hour, the more people we have out loooking and searching the quicker we can bring him home
“Thank you all soo much for the support so far, it means a lot.”
There have been reported sightings of Martin but as yet he has not been found.
Police say the 26-year-old is from Blighs Gardens in Derry.
“His family have not seen him since last Sunday and we are concerned for his safety. Martin is 6ft 1, slim build with brown hair, we do not know what he is wearing,” said PSNI Foyle.