Proteus

Also called The Old Man In The Sea, Proteus was a seer and son of Poseidon who knew everything about the past, present and future, but did not like to tell the future to anyone. To learn it from him you had to seek him up at Pharos in Egypt where he lie with the seals and hold on to him while he took different terrible shapes. If you managed he would turn into his normal shape and tell you what you needed to know.