Update 4.30pm: Louise James, who lost her partner Sean and four family members in the tragedy, has spoken of how she felt something was not right on the day that her family were hit by tragedy.
In a statement which was read at the inquest she said she was about to fly home from a hen weekend in Liverpool when the incident happened.
At 6.55pm she rang her daughter Jodie and she said they were in Buncrana at a play park by the shore.
A short time later Ms James said: "I got a feeling that something was not right.
"I tried to contact Sean and Jodie but their phones would not connect."
She rang her brother Nathan, asking had her mother come home, and he said she had not.
When her plane landed in Belfast her brother Joshua told her what happened.
She went directly to a hotel in Derry, saw her baby and was taken to identify the victims.
The inquest has also heard this afternoon that post-mortem results for the driver of the car show he may have been three times over the drink-driving limit.
A pathologist who examined Sean McGrotty's body says the results of the post-mortem indicate there may have been an element of intoxication.
Pathologist Dr Catriona Dillon said that on examining the body Dr Dillon found 159 milligrams per decimetre of alcohol in Mr McGrotty's blood.
The legal limit is 50 milligrams per decimetre.
The pathologist told the inquest she couldn't indicate if the alcohol-impaired Mr McGrotty's driving as it depended on a number of factors including whether he was a habitual drinker.
But she said the levels of alcohol found might indicate an element of intoxication involved.
Mr McGrotty was behind the wheel when his car entered the water at Buncrana pier last year, in an incident that saw him, his two sons, their grandmother and her daughter to lose their lives.
The inquest also heard it would have cost €400 to clear algae from Buncrana Pier, an expert report said.
The treacherous bloom was as "slippery as ice" when the family car slid into the water last year, an eye witness said.
No barrier prevented people from accessing the slipway and no signs were displayed warning specifically of the danger.
A risk assessment had not been carried out for 15 years, lawyer Keith O'Grady said.
He added: "In 2016 you have open access to a slipway covered in algae and in 2017 you have the slipway power-washed, cleaned, in excellent condition, and the gate closed and nobody can go down."
John McLaughlin, a director at Donegal County Council, said the purpose of cleaning the slipway was to facilitate a ferry which used it during the summer but not in the winter.
The council commissioned consultants to draw up a report following last year's tragedy.
Mr McLaughlin added: "The €400 talks about removing it (algae) once but it does not say the frequency of removal so that will be a matter for Donegal County Council and the total cost but certainly €400 seems low."
He said during winter the slipway was rarely used.
He added that drivers using the flat section of the pier had a good view of the algae closer to the watermark.
Following an investigation the intention is to keep the gates open.
They were installed to control boarding of the ferry.
He said the council was doing everything in its power within its budget to ensure no repeat of the tragedy.
Update - 1.15pm: Former footballer Davitt Walsh, who swam out into the harbour in an effort to save the six occupants of the Audi Q7, said he had been aware that the algae would be slippery, but that a stranger would not have been aware of the dangers.
When he realised the situation he swam straight to the car.
As he arrived, Mr McGrotty smashed a window in the car.
The father handed him the baby then sat out of the vehicle on the window ledge, his head and shoulders were out and his hands on the roof - but his legs were still inside, Mr Walsh said.
At that stage water which had been seeping in turned into a surge.
Mr Walsh said: "It was like a wave rushing in...it gushed in."
He added: "I saw a young boy inside the car trying to clamber out past the driver.
"I reached in and grabbed the wee boy, I tried to pull the wee boy out but he seemed to get stuck on something.
"When the driver sat on the window ledge I remember the car tilted and the water then started to gush into the car.
"Just as I was trying to pull the wee boy out of the car the water rushed in and I had to let go.
"The father climbed back into the car, looked back and me and said 'save my baby'.
"The water gushed in and the car went under the water."
He added: "I had to let go because I was struggling as hard as I could to avoid getting sucked into the water."
When he made it back to the slipway and handed the baby to his girlfriend, he collapsed with exhaustion and had to be helped from the slippery surface.
He said: "I could hardly breath, I was so tired."
It was freezing cold and he suffered cuts to his feet which he was treated for in hospital.
Garda Sergeant Mark Traynor said gardaí were on the scene within four or five minutes of the call but by that stage there was no sign of the car.
He said gardaí were at the back gate of the station when they received the call.
He added that the RNLI responded within a similar time as its members were returning from an exercise.
Coroner Denis McCauley said: "It is a really short time."
Garda Traynor also agreed that the algae was thick and very slippy on the pier and that his colleagues were also very aware of this.
Solicitor for Donegal County Council, Mr Michael Staines, said that almost every pier had algae on it.
"The algae was very evident," added the Garda.
During cross examination, Sgt Traynor told the inquest that a file had been prepared on the incident and sent to the Director of Public Prosections.
He said the recommendation from the DPP was that nobody was to be prosecuted as a result of the tragedy.
The inquest was told that the gate leading down to the slipway was open at the time and cars were freely allowed to enter onto it.
The only signage on the day was warnings not to swim within 15 metres of the pier.
Sgt Traynor said a life buoy was used during the incident.
Since then additional buoyancy aids have been installed and a gate prevents cars from parking on the slipway, lawyer Keith O'Grady told the inquest.
He said it appeared tyre marks on the slipway were those of the victims' vehicle.
No prosecutions were taken in the case.
Mr O'Grady said the only sign at the time was one warning people not to swim within 15 metres of the slipway.
Sgt Traynor said additional signage had since been installed.
Update - 12.05pm: Emergency services called after a car plunged off a pier in Buncrana arrived within 12 minutes, an eyewitness has said.
By the time the RNLI lifesavers reached the scene the Derry family's car had disappeared into Lough Swilly and the victims were floating in the water, Francis Crawford told an inquest into the tragedy.
There was no suggestion the speed of the response was inappropriate.
He added: "The car was floating, bobbing in the water, 10 to 15 yards from the slipway, and slowly floating, bobbing off to the right of the slipway.
"I could still hear people and the child screaming from the car, all the time the car must have been taking on water.
"I was hoping that the emergency services would arrive and the car would not go down."
He added: "I could hear sirens, the nose of the car dipped...and the car sank to the bottom."
Mr Crawford had called the Coastguard for help after Sean McGrotty urged him to seek emergency assistance.
He asked for the coastguard service and was immediately put through to the Malin Head Coastguard Station.
He told the coastguard member, Mike Mullin, that a car was in the water off the pier with a family in it and that a tragedy was about to happen.
The witness said it took 12 minutes for the RNLI to arrive.
Mr Crawford added that during that time he heard the squeals and crying of children inside the car.
Then a man and a woman arrived on the scene.
Mr Crawford asked the man, who later turned out to be Davitt Walsh, if he could swim and he replied he could.
He pleaded with Mr Walsh to try and swim out to the car.
Mr Walsh, who was along with his girlfriend Stephanie Knox, stripped down to his boxer-shorts, and swam out to the troubled car.
Mr Crawford said he continued to hear screaming from those inside but he soon saw Mr Walsh coming back to the slipway with a baby in his arms.
He said Mr Walsh told him that he tried to get another boy out but that his leg had got caught.
He added that he hoped Mr Walsh would be able to return to the water but that he was simply exhausted.
Mrs Kay Crawford gave similar evidence to that of her husband.
She added that she noticed there were tyre marks on the slipway but she said she could not say if it was from Mr McGrotty's vehicle.
Green algae had covered the slipway.
The first witness to the inquest in Buncrana added: "It was treacherous to walk on, slippery as ice."
Update - 10.46am: The inquest into the Buncrana pier tragedy has opened in Co Donegal, writes Stephen Maguire.
A large attendance of Gardai, members of the RNLI, family members, members of the legal profession, members of Donegal County Council and others are present at the Lake of Shadows Hotel in the seaside town.
The inquest, which will hear evidence from 12 witnesses on the tragic events, is expected to last two days.
Five family members drowned on March 20, 2016, when the Audi Q7 car they were in slid off the pier and into the water.
Those who lost their lives were Sean McGrotty, his sons Mark, 11 and eight-year-old Evan, his mother-in-law Ruth Daniels and her teenage daughter Jodie-Lee Tracey.
Baby girl Rionaghac-Ann was saved when her father passed her out the window to local man Davitt Walsh who bravely tried to come to the family’s aid.
Over the next two days, the inquest will try to establish exactly what happened on that evening.
Louise James, who lost her partner Sean and four family members in the tragedy, has said she is hoping the two days will pass soon so she and her baby girl can get on with life.
Louise told her priest, Father Paddy O'Kane in Ballymagroarty, that she is taking each day as it comes.
Father O'Kane said he called with Louise a few days ago and revealed how Louise, from Derry, said she wanted to then get on with her life along with her baby Rioghnach.
Coroner Denis McCauley will oversee the inquest hearing today, where a jury will be sworn in to hear evidence from 12 depositions.
Before the inquest opened, Dr McCauley took the jury to a separate room to address them on their duties.
He opened the inquest by addressing those present and explaining the format the inquest will take.
He said those present had an important and solemn duty to do.
He asked the media to be very sensitive and to report the inquest in the most honest and non-sensational way.
No running order of witnesses has yet been given.
However, among those who will take the stand are Francis and Kay Crawford, Davitt Walsh, Garda Sgt Mark Traynor, John Leech of Irish Water Safety, Louise James, Garda Seamus Callaghan, Garda Damien Mulkearns, Robert Gray from Audi Ireland and John McLaughlin from Donegal County Council.
The inquest will also examine reports by Donegal County Council into their piers and slipways, with input from Irish Water Safety Authority and the Road Safety Authority of Ireland.
A report from Volkswagen Ireland has also been prepared for the inquest.
A large media presence has gathered at the inquest for the hearing.
Earlier: The inquest into the Buncrana pier tragedy will begin this morning.
The Coroner for Donegal says they will aim to establish exactly what happened on the day five members of one family lost their lives.
On March 20, 2016, a car slid off Buncrana pier and into the waters of Lough Swilly.
Five members of one family were killed in the incident - 49-year-old Sean McGrotty, who was driving the car, his sons 12-year-old Mark and eight-year-old Evan - their Grandmother Ruth Daniels and her 14-year-old daughter Jodie Lee.
Former footballer Davitt Walsh swam out into the harbour in an effort to save the six occupants of the Audi Q7.
Sean McGrotty handed his four-month-old baby daughter Rionaghac-Ann to Mr Walsh through the broken driver's side window just moments before the vehicle sank.
Mr Walsh has been awarded a gold medal for bravery at sea.
The inquest into their deaths starts this morning with 12 witnesses due to give evidence.
It will try to establish exactly what events led to the tragedy.
The inquest at a hotel in the town also intends to look into the conditions of all piers and slipways in Donegal, and at guidelines for people whose cars end up in the water.
The Coroner Dr Denis McCauley has described what happened there as one of the worst family tragedies on the Irish coast in living memory.