After Jesus has sent out his disciples to preach to the towns of Galilee (probably around the second year of his public ministry), they return to him and give him reports of what they accomplished. Jesus, seeing they need rest, takes them to a desolate place so that they can be alone.
Mark notes that this is a busy time, for “many were coming and going.” In the parallel account in the Gospel of John, we read that the Passover Festival was near, so this would explain why there were huge crowds of people “coming and going” during this time.
As Jesus and the disciples travel by boat on the Sea of Galilee to a remote place, a crowd of people spot them and follow along on land. Evidently, their boat was close to land and could easily be seen from the shore of the lake.
In verse 34, when their boat goes ashore, Jesus sees the great crowd that has followed them and he has compassion on them, first by teaching them and then by feeding them. James A. Brooks writes, in vol. 23, Mark, The New American Commentary,
’Sheep without a shepherd’ is an Old Testament picture of Israel without spiritual leadership (Num 27:17; 1 Kgs 22:17; Ezek 34:5). Jesus is pictured as the Good Shepherd who feeds the new Israel (cf. Ezek 34:23; Jer 23:4). First he ‘fed’ the crowd with his teaching. Mark frequently emphasized that Jesus taught.
The miracle that follows is recounted in all four Gospels, so the early church obviously considered the feeding of the five thousand to be an extremely important event in Jesus’ ministry. The only other miracle attested by all four Gospels is the resurrection of Jesus.
Because it was late in the evening and they are in a desolate region, the disciples ask Jesus to send the crowds away to buy food for themselves. Jesus responds by telling the disciples to feed the crowd. They complain that it would take 200 denarii to feed a crowd this size (between 15-25,000 people total).
One denarius was equivalent to an average worker’s daily wage. The average daily wage of an American today is about $210, so that would equate to about $42,000! Most of us don’t have $42,000 sitting around to feed a crowd of people who have come to hear us speak for free, so the disciples are understandably panicked.
Unperturbed, Jesus asks them to see how many loaves of bread they can find among the crowd, and they return with five loaves and two fish. Jesus instructs the crowd to divide themselves into groups of fifties and hundreds and sit down on the “green grass.” Note that the grass would have only been green in the spring around the time of Passover, so this little detail nicely harmonizes with the Gospel of John’s timing of this miracle.
Jesus then says a blessing over the food and sends the disciples into the crowd with bread and fish. When they return, everyone in the crowd has been fed and there are twelve baskets left over with bread and fish.
This miracle account refers in several ways to the Old Testament, as noted by James Brooks:
As already observed in the comments on 1:4, in the Old Testament the desert was the place where God met, tested, and blessed his people. Specially important was the experience of Israel in the wilderness following the Exodus. After the testing involved in that experience, ‘rest’ was promised. Note how Mark introduced that idea (v. 31). Also the ‘sheep without a shepherd’ (v. 34) recalls Moses’ description of Israel in Num 27:17; and the ‘hundreds and fifties’ of v. 40, the organization of Israel in Exod 18:21, not to mention the resemblance between the loaves and the manna. The literal rest in the desert and later in the promised land following the Exodus did not satisfy, and the prophets and psalmists began to look forward to a better rest in the messianic age. . . . Mark saw in Jesus’ feeding of the five thousand an eschatological Moses giving perfect rest to and supplying all the needs of his people. The feeding anticipates the messianic banquet at the end of the age. The kingdom is at hand. The miracle as such is not as important for Mark as what it reveals about Jesus. . . .
The prophet Elisha performed a similar miracle according to 2 Kgs 4:42–44. In fact, Mark’s wording owes something to this account and possibly 1 Kgs 17:9–16. Mark may also have seen in the event Jesus as the fulfillment of the law and the prophets.
Immediately following the miracle of the feeding of five thousand, Jesus sends the disciples back into their boat to travel across the northern tip of the Sea of Galilee to meet him in a town called Bethsaida. Jesus goes by himself up on a mountain to pray alone.
Between 3 and 6 am, Jesus sees the disciples rowing their boat against the wind (they have gone way off course and are stuck out in the middle of the lake.) Jesus decides to go to them by walking on the lake. As he approaches the boat, they see him and think he is a ghost.
Jesus tells them, “Take courage! It is I. Don’t be afraid.” John D. Grassmick, in The Bible Knowledge Commentary, remarks:
The words It is I (lit., ‘I am,’ egō eimi) may simply convey self-identification (‘It is I, Jesus’), but they are probably intended here to echo the Old Testament formula of God’s self-revelation: ‘I am who I am’ (cf. Ex. 3:14; Isa. 41:4; 43:10; 51:12; 52:6).
Jesus climbs into the boat and the winds calm down. Mark records that the disciples are amazed because they did not understand who Jesus really was, even after seeing Jesus feed five thousand people.
The miracle of Jesus walking on the Sea of Galilee is recorded in Matthew, Mark, and John. Only Luke does not record it.