Dim dtb1 As New DataTable("Table1")
dtb1.Columns.Add(New DataColumn("Column1", GetType(Integer)))
dtb1.Columns.Add(New DataColumn("Column2", GetType(Integer)))
dtb1.Columns.Add(New DataColumn("Column3", GetType(Single)))
dtb1.Columns.Add(New DataColumn("Column4", GetType(String)))
dtb1.Columns.Add(New DataColumn("Column5", GetType(String)))
dtb1.Rows.Add(1, 1, 1.1, "1", "5")
dtb1.Rows.Add(2, 2, 2.2, "2", "4")
dtb1.Rows.Add(3, 3, 3.3, "3", "3")
dtb1.Rows.Add(4, 4, 4.4, "4", "2")
dtb1.Rows.Add(5, 5, 5.5, "5", "1")
dtb1.Rows.Add(11, 11, 11, "11", "11")
Dim strOutput(dtb1.Rows.Count - 1, dtb1.Columns.Count - 1) As String '(row,col)
For intRow As Integer = 0 To dtb1.Rows.Count - 1
For intCol As Integer = 0 To dtb1.Columns.Count - 1
strOutput(intRow, intCol) = CStr(dtb1.Rows(intRow).Item(intCol))
Next intCol
Next intRow
Или вы можете использовать List (Of String ()) вместо двумерного массива:
Dim lstOutput As New List(Of Object()) From {dtb1.Rows(0).ItemArray, dtb1.Rows(1).ItemArray, dtb1.Rows(2).ItemArray}