Summary: 1) A New Trail (Isaiah 43:16–17), 2) A New Thought (Isaiah 43:18), 3) A New Thing(Isaiah 43: 19a), and 4) A New Tender (Isaiah 43:19b-21)
Have you ever gone on a journey not knowing where exactly you would end up? When Lisa and I went on our honeymoon, we left home with a general vicinity in mind, but the route and ultimate destination was to be determined. All we knew is that we loved each other, we were going together and we would enjoy the experiences together.
For the people of God in Isaiah 43, Israel was presently in captivity in Babylon, but there was a new horizon before them. God promises that his people will be released from exile through a new exodus. He was their God and He desired to show forth His glory through them in their deliverance. As glorious as the exodus from Egypt was, a new journey was before them even greater than before. All these events recorded in chapters 40–55 of Isaiah are believed to have occurred from the middle of the sixth century (Crossway Bibles. (2008). The ESV Study Bible (p. 1233). Wheaton, IL: Crossway Bibles.)
We don't know what exactly lies before us, but we too are in captivity. Sin holds us back from everything God wants and the full delight He desires for us. He promises great and marvelous works, doing it in ways we can't even imagine. But we need to discern the path to take, with a God-centered mindset.
Isaiah 43:16-21 shows us who this God is that goes with us towards this New Horizon. For a people in captivity, God shows: 1) A New Trail (Isaiah 43:16–17), 2) A New Thought (Isaiah 43:18), 3) A New Thing (Isaiah 43: 19a), and 4) A New Tender (Isaiah 43:19b-21)
1) A New Trail (Isaiah 43:16–17)
Isaiah 43:16–17 Thus says The Lord, who makes a way in the sea, a path in the mighty waters,  who brings forth chariot and horse, army and warrior; they will lie down, they cannot rise; they are extinguished, quenched like a wick: (ESV)
In the context of Isaiah 43, this is a prophetic prophecy which looks beyond the overthrow of present enemies to the return home for a people of God. The description is obviously related to the exodus. But it is not so much the events themselves we are invited to reflect on as it is the power, the love, and the dependability that the Lord demonstrated in those events (Oswalt, J. N. (1998). The Book of Isaiah, Chapters 40–66 (p. 154). Grand Rapids, MI: Wm. B. Eerdmans Publishing Co.).
• In considering a way forward, we must have a true destination in mind. It does no good to merely seek to eliminate present difficulties, if we fail to figure out what we hope to gain. In essence we can gain everything we might immediately desire and not achieve any lasting godliness. In God's economy, we often must persevere through difficulties to achieve true holiness and success in His kingdom.
In verse 16, God reminds His people of what he did at the time of the Exodus from Egypt, providing them with a path through the sea and at the same time destroying the Egyptian army. The 6th century B.C. is also a time when naval power becomes a military factor. In the Aegean and eastern Mediterranean, powerful Athenian and Phoenician fleets serve Egyptian and Persian interests in seeking control of the shipping lanes. Yahweh claims control of forces at sea, as well as those on land. But eventually they will all be extinguished like a wick (Watts, J. D. W. (1998). Isaiah 34–66 (Vol. 25, pp. 134–135). Dallas: Word, Incorporated.).