Conversation so far:
Was types of exploration happened before da Gama?
From the earlier part of the 15th century, Portuguese expeditions organized by Prince Henry the Navigator had been reaching down the African coastline, principally in search of west African riches.
Were any riches found?
They had greatly extended Portuguese maritime knowledge, but had little profit to show for the effort.
After Henry's death in 1460.
What happened after Henry's death?
the Portuguese Crown showed little interest in continuing this effort and, in 1469, sold off the neglected African enterprise to a private Lisbon merchant.
What was the result of neglection of the African enterprise?
Within a few years, Gomes' captains expanded Portuguese knowledge across the Gulf of Guinea, doing business in gold dust, Melegueta pepper, ivory and sub-Saharan slaves.
What was the most profitable trade?
To break the monarch's dependence on the feudal nobility, John II needed to build up the royal treasury.
Are there any other interesting aspects about this article?
Under John II's watch, the gold and slave trade in west Africa was greatly expanded.
He was eager to break into the highly profitable spice trade between Europe and Asia.
Who were some of this trade partners?
At the time, this was virtually monopolized by the Republic of Venice, who operated overland routes via Levantine and Egyptian ports.
Who headed the explorations?
John II set a new objective for his captains: to find a sea route to Asia by sailing around the African continent.
Was he successful?
By the time Vasco da Gama was in his 20s, the king's plans were coming to fruition.
In 1487, John II dispatched two spies.

Question: What did the spies do?
Self-contained rewrite: What did the John II spies do?