Prince Philip's association with the Royal Navy and love of the sea will be a focus of the Windsor Castle ceremony.
But no sermon will be delivered, in line with his wishes.
More than 730 members of the armed forces are taking part in the event, but there is a limit of 30 mourners at St George's Chapel, under Covid rules. None of the mourners wearing military uniform today.
Other sad news
Helen McCrory: Peaky Blinders actress dies aged 52
"She was also a gifted actor - fearless and magnificent. She elevated and made humane every scene, every character she played,"
A very sad time for the Queen, she must be devastated after someone she has loved since a 13yo & 73 years of marriage,
Also RIP Helen, a very fine actress & far too young to die.