John Gill Commentary John 21:1

"After these things Jesus manifested himself again to the disciples at the sea of Tiberias; and he manifested [himself] on this wise." — John 21:1 (ASV)

After these things
The resurrection of Christ from the dead, his appearance to Mary Magdalene, and twice to his disciples; once when Thomas was absent, and at another time when he was present:

Jesus showed himself again to the disciples ,
a third time, as in (John 21:14) though not to them all; seven are only mentioned, as together, when he appeared to them:

at the sea of Tiberias ;
the same with the sea of Galilee; see (John 6:1) for after the second appearance of Christ to his disciples, they went from Jerusalem to Galilee, by the order of Christ, who appointed to meet them there, (Matthew 28:10Matthew 28:16)

and on this way showed he himself ;
the manner in which he made his appearance, and the persons to whom, are as follow.