```ts
export function tideMarks(levels: number[]): number[] {
  if (levels.length <= 2) return []; // No peaks in a list of length 1 or 2

  const result: number[] = [];
  for (let i = 1; i < levels.length - 1; i++) {
    if (levels[i] > levels[i - 1] && levels[i] > levels[i + 1]) {
      result.push(i);
    }
  }

  return result;
}
```