Porthdinllaen RNLI lifeboat and station named
A double naming ceremony at the RNLI's Porthdinllaen station later will also mark 150 years of life-saving by the charity at the Llŷn peninsula base.
BBC presenter David Dimbleby is among those doing the honours as the £9.8m new boathouse is formally opened.
He will officially name its £2.7m Tamar class lifeboat the John D Spicer, after a late friend and RNLI governor.
The RNLI has invested a total of £54m around Wales over the past two years, including four new slipway boathouses.
The Porthdinllaen station opened its doors to the public over the Easter weekend.
The John D Spicer arrived at the station in August 2012 and has launched on service 32 times since then.
In addition to the naming ceremonies, the event will see the charity presenting its thanks inscribed on vellum for 150 years of volunteering at the station.
Lifeboat operations manager Ken Fitzpatrick said: "A dedication service is a historic event for all coastal communities - it's a chance for us to personally thank the donors and their families by showcasing the lifeboat's capability so they can see the difference their loved ones legacies will make by saving lives at sea.
"But Sunday will be extra special for us all since it's a triple celebration and the official start to a new chapter in Porthdinllaen RNLI's history."
Other guests at the event include the Bishop of Bangor, Andrew John.