Yes.
sea
Generally speaking, Constantinople was not a likely place for Vikings to travel to. If any peoples from Northern Europe wished to travel there, it would require a voyage south to the Straits of Gibraltar and sail eastward in the Mediterranean Sea. After reaching the Aegean Sea, it would require a land trip to reach Constantinople.
Mediterranean sea
Yes, either from Black Sea or Mediterranean Sea.
portgaul
Ukraine does not border the Mediterranean. At best, Ukraine would have to use one of its Black Sea ports and then have the ship travel through the Bosporus, into the Sea of Marmara, into the Dardanelles Straits, and through the Aegean Sea to get to the Mediterranean Sea.
The North Sea, and the Atlantic Ocean.
Portugal
portugalPortugal
The Mediterranean Sea.
PortugalPortugal
all the european coasts, and the black sea