Ya fantasy mistery book about 3 teens and a ship

In 2014. I read the book from fantasy section that was recomended as something similar to Harry Poter series. I believe that the original was written in English and I read translated version on Serbian.Story followed a boy who lived in some small city. One summer in the house on the outskirts that was by the sea or on the cliff brother and sister (probably twins) came to spend the vacation with their misterious uncle/granpa(l am not sure). I don't remeber much. They became friends and one day the brother slipped and almost fell off of a cliff, but he managed to hold onto the rocks and during that he noticed a hole in a cliff where he saw a diary that led to the cave that had a ship in it or was there just a peak in a cave itself. I remeber that the ship was significant and had pretty cool name. It might have had time traveling abilities. The book was part of the series and one of the other was about egypt (I know this bc on the last page there was a preview of other books from the series). This is pretty much all I remember other than that the title was long. I tried chat gpt but it was not able to identify it and I moved out of the town I used to live in where I rented the book. It was for teenagers, and it was definetly fantasy and mistery book. Sorry for the format and language mistakes, I am still learning English and l'm writting on my phone.