The Egyptians were notorious for not having great wood, and consequently they could not build large, sturdy ships. There were only two different kinds of trees native to Egypt during that time. One was too soft for shipbuilding, the other was too small for larger ships. They built rafts instead for use in the Nile River.
The Egyptians instead hired the Phoenicians for their sailing expeditions. One famous example was during the reign of the pharaoh Necho II. During his reign, the Egyptians were under attack by the Babylonians, and he wanted to find a way to attack southern Babylonia by sea. He first wanted to build a canal between the Nile and the Red Sea, but discovered that he was giving free access to his enemies too. Instead, he hired Phoenician sailors to find a way to circumnavigate Africa at circa 600 BC.
Necho II asked for Phoenician assistance because the Phoenicians (who lived in modern Lebanon) were excellent sailors and had several colonies in the West, such as Carthage and the islet of Mogador opposite modern Essaouira. The Phoenicians must have been happy to help the Egyptians, because they shared the Babylonian enemy. Here is Herodotus' account of the vovage, in a translation by Aubrey de Sélincourt.
Herodotus' story:
Libya is washed on all sides by the sea except where it joins Asia, as was first demonstrated, so far as our knowledge goes, by the Egyptian king Necho, who, after calling off the construction of the canal between the Nile and the Arabian gulf, sent out a fleet manned by a Phoenician crew with orders to sail west about and return to Egypt and the Mediterranean by way of the Straits of Gibraltar. The Phoenicians sailed from the Arabian gulf into the southern ocean, and every autumn put in at some convenient spot on the Libyan coast, sowed a patch of ground, and waited for next year's harvest. Then, having got in their grain, they put to sea again, and after two full years rounded the Pillars of Heracles in the course of the third, and returned to Egypt. These men made a statement which I do not myself believe, though others may, to the effect that as they sailed on a westerly course round the southern end of Libya, they had the sun on their right - to northward of them. This is how Libya was first discovered by sea.
The reason Herodotus gives for disbelieving the story is the sailors' reported claim that when they sailed along the southern coast of Africa, they found the Sun stood to their right, in the north; Herodotus, who was unaware of the spherical shape of the Earth found this impossible to believe.
Most modern historians claim that the Phoenicians did in fact successfully circumnavigate Africa. If it is true, then they would've been the first to circumnavigate Africa 2,000 years before the Portuguese. The journey was extremely difficult for the Portuguese. The fact that the Phoenicians were able to do it is a testament to their sailing capabilities. Further, because the Phoenicians circumnavigated Africa, it is very likely that they were also the first to know that the Earth was a sphere.
As far as most legendary Egyptian expeditions go, the circumnavigation of Africa is their greatest. Of course, they couldn't have done it without Phoenician expertise.
There's always room for discussion, but perhaps the section Travel and contact across the Atlantic before Columbus from our FAQ will answer your inquiry.
You may also be interested in this previous topic regarding the supposed evidence of tobacco and coca found on Egyptian mummies.