CREATE TABLE table_48279 ("Date" TEXT, "U-boat" TEXT, "Name" TEXT, "Nationality" TEXT, "Tonnage  ( GRT ) " FLOAT, "Fate" TEXT)

Which Tonnage (GRT) is the highest one that has a Date of 16 june 1940?
SELECT MAX("Tonnage (GRT)") FROM table_48279 WHERE "Date" = '16 june 1940'
SELECT MAX("Tonnage (GRT)") FROM "table_48279" WHERE "Date" = '16 june 1940'