NARRATOR: As a new day begins on Oak Island--
LAIRD NIVEN: I want to clean this side out a little bit,
see if we can pick things up.
NARRATOR: Archaeologist Laird Niven, along with geologist
Terry Matheson and heavy equipment operator Billy
Gerhardt, are continuing to excavate
the area inside the so-called U-shaped structure,
a structure they believe could have been built centuries ago.
TERRY MATHESON: Whoa, interesting.
Looks like a post sticking straight up.
LAIRD NIVEN: Yeah, it is.
TERRY MATHESON: Laird, take a quick look.
Billy just clipped what looks like perhaps
a post sticking straight up.
It was pretty vertical.
What do you figure?
LAIRD NIVEN: It's actually-- that's a third piece of wood.
TERRY MATHESON: It starts to become
kind of an interesting-looking something.
More than just a plank or two.
Maybe a structure.
NARRATOR: Planks of wood buried within the U-shaped structure.
Could they be a previously-undiscovered part
of this ancient formation?
Or could the team have just found an entirely
new structure at Smith's Cove?
LAIRD NIVEN: I think it would be wise just to leave it
and let Rick take a look at it.
TERRY MATHESON: That's probably a good point.
We could dig around it a bit and try to--
but no heavy-duty stuff, maybe.
Whoa, yeah, yeah.
This is it here.
We got something going on here.
LAIRD NIVEN: Yeah, you can see the top of--
TERRY MATHESON: Gently, gently.
We're going to see what we can see here.
Looks like timbers on edge.
BILLY GERHARDT: It's not one-inch planks.
Like, it's thick enough to be a wall.
LAIRD NIVEN: Odd construction.
TERRY MATHESON: Very odd.
LAIRD NIVEN: They're offset.
TERRY MATHESON: Looks like it's built for strength.
LAIRD NIVEN: Pretty big.
TERRY MATHESON: Pretty big and pretty interesting.
MAN: Heads up, guys.
MARTY LAGINA: What do you got?
MAN: We don't know.
TERRY MATHESON: We started right down here.
And then the next thing is-- hold it now-- what's this?
MARTY LAGINA: Wow, that's pretty cool.
TERRY MATHESON: You know, quite a significant wall.
NARRATOR: A wooden wall buried at Smith's Cove?
But if so, who built it, and for what purpose?
JACK BEGLEY: How deep do these go?
Any idea?
MAN: We're not sure yet.
TERRY MATHESON: It's possible they're
trying to hold back water from entering the flood zones.
MARTY LAGINA: Makes you wonder what you're going to find
back there a little ways.
But this definitely isn't on any map.
MARTY LAGINA: No, this is a new find.
This is totally undiscovered.
So we're finding these walls that nobody else has ever
found, which in a sense is a piece of evidence
that perhaps it could be original because somebody doing
it originally would have been scrupulous about clearing up
evidence.
And we're going to dig it up and see what it is.
RICK LAGINA: There.
What are we looking at?
MARTY LAGINA: You tell me.
It's a wooden wall.
MAN: That's well built.
RICK LAGINA: Oh yeah.
It's pretty impressive.
A little bit of blue clay on it.
MARTY LAGINA: Oh, no, there was a lot.
They scraped it away.
RICK LAGINA: Here.
See this here?
MAN: It looks like stacked racks.
MAN: There were rocks down there.
MAN: Are we starting to get into the French drain?
NARRATOR: A French drain?
JACK BEGLEY: This is packed with stones right here.
And just next to it was virgin soil.
NARRATOR: Two years ago while searching for evidence
of the box drains at Smith's Cove,
the team discovered layers of rounded stones
forming what they believe to be a French drain--
an ancient irrigation system used to control
and direct the flow of water.
MARTY LAGINA: I'm going to put you on the spot now.
Man-made?
MAN: I believe so, yeah.
NARRATOR: Could these stones be another part
of a French drain system constructed
centuries ago at Smith's Cove?
And if so, could it mean the team is closer
than ever to finding one of Oak Island's legendary flood
tunnels?
RICK LAGINA: Really, well, we should just
go at this real light, Laird, and just see
if this really is something.
NARRATOR: For Rick, Marty and their team,
the discovery of another French drain at Smith's Cove
could prove to be their biggest breakthrough in the 12 years
since they began searching for treasure on Oak Island.
But as the Laginas and their partners continue to follow
the flood system further--
and deeper down into the money pit--
where will it lead them?
To a treasure vault filled with gold and jewels?
Or will they discover that as they get closer to solving
a 223-year-old mystery, the island
will fight harder than ever to protect its buried secrets?