The adventure to Treasure

I received a letter from an unknown person,

It was a map,

X marks he spot was written,

It was in a beach in Britain.

I had to find the treasure,

And off I went to Sunny side beach,

To find the hidden teasure,

I arrived at the beach.

I couldn't find the x,

Then I saw a black x,

I started digging and digging but nothing was found,

When I walked I couldn't find x .

In the distance I saw a flag,

It had a x,

I ran as fast as a cheetah to the spot,

I came closer I grabbed my shovel,