Earliest known search in water started in Lake Nemi near
Rome. In 1446, Italian architect Leon Batista Alberti searched for two Roman
vessels sank at the lake. Since he only found mere pieces of wood, he didn't
draw to much attention.
In 1535 Alberti's successor used first time an instrument
which was a wooden bell girded by metal. This special device which left the
divers hands free was extremely useful.

1802 British Ambassador, the Earl of Elgin ordered that the freezes
of Parthenon to be taken to England. The ship which was carrying the cargo
sank near the Kytera with its precious cargo. Skin divers form Samos were
hired to rescue the freezes. Just holding their breath, Samos divers rescued
the freezes. In 1816 Lord Elgin sold them to British Museum where these are
still displayed.

1819 German inventor August Siebe invented divers helmet
which was miniaturized version of diving bell. This copper helmet which only
covered the head was fed by a pump from the surface. This device obliged the
divers to stand upright, if not their helmet would be filled with the water.
1827 Annesio Fusconi used diving bell which had 2.5 meters
diameter for the Roman shipwrecks at the Lake Nemi.
1836 Deane Brothers who worked as salvage divers for British
Government discovered remains of Mary Rose, British ship with historical
significance. Mary Rose had been captized by the French Fleet in 1545.
1839 A. Siebe added watertight suite to his helmet. This
great invention which gave great mobility to divers was used for nearly a
century.